Annual reports of Boots Essay Example | Topics and Well Written Essays - 2000 words

Annual reports of Boots - Essay Example Return on capital employed has dropped from 18.15% in 2004 to 13.95% in 2005. Gross profit margin shows how much profit was made out of every dollar of sales before covering operating expenses. The gross profit margin has only improved very slightly from 45.67% in 2004 to 46.05% in 2005. Net profit margin shows how much profit was made out of every dollar of sales after covering all costs and expenses. The net profit margin has decreased from 7.73% in 2004 to 5.53% in 2005. Return on assets shows how much profit was earned out of every dollar of total assets. Return on assets has declined from 11.75% in 2004 to 8.76% in 2005. Return on owners' equity shows profit available to equity owners out of every dollar of their investment. Return on owners' equity has also decreased from 22.76% in 2004 to 18.78% in 2005. The downward trend of the profitability ratios indicates weakness. Liquidity ratios are indicators of short-term financial stability. They show whether the business is able to meet its current debt obligation. The liquidity ratios include current ratio and acid test ratio. The current ratio shows the company's ability to meet its current debt obligations (due within 12 months) with assets that can be converted into cash within a short period. Though the current ratio has decreased from 1.5170 in 2004 to 1.4671 in 2005, it is still considered satisfactory being more than 1. This means that the current assets can cover current liabilities with a margin of safety. If the ratio is too big, it may mean that the firm has too much liquidity and is not optimising its investment opportunities. The acid test ratio shows whether the firm has sufficient liquid resources (assets that can be converted into cash very quickly) to meet its current liabilities. The acid test ratio indicates weakness as it has decreased from 0.9086 in 2004 to 0.8027 in 2005. The rati os in both years are less than 1, which means that the company may have difficulty in meeting its short-term financial claims with its liquid assets. Use-of-assets ratios indicate operating efficiency and how well the assets

What is Public health and Community health Essay Example for Free

What is Public health and Community health Essay Public Health is an aspect of Health Services concerned with threats to the health of the population of a community based on population health analysis. It generally includes surveillance and control of infectious disease and promotion of healthy behaviors (health promotion) among members of the community. Both vaccination programs and free distribution of condoms are Public Health measures. Public Health promotes not simply the absence of disease but mental, physical and emotional well-being (Public Health). Community Health is a discipline that concerns itself with the study and the betterment of the health characteristics of a given community. While the term community can be defined, community health tends to involve everyone working together (Public Health). What is type of structure and function at each level of government? The type of structure of each level of government and their functions tend to overlap in regard to how the dilemma of teenage pregnancy is handled. Although on a national level, in 2006, in more than 10 years, for the first time, teenage pregnancy increased to 3% from 2005 to 2006. At a state level, in 2005, Texas had the highest number of teenage births accounting for 62 births per 1000 women, in addition to New Mexico, Mississippi, Arkansas, and Arizona possessing the same number of teenage pregnancies. New Hampshire was the state with the lowest teenage births, 18 births per 1000 women, in addition to Vermont, Massachusetts, Connecticut, and New Jersey possessing the same number of teenage pregnancies (Hamilton, 2009). From a local level, it is like trying to figure out, which came first, the chicken or the egg? Some causes of negative outcomes for teenage pregnancy are educational failure, poverty, unemployment, and low esteem could result from early child bearing before the female is ready. In 2006, a study conducted, has released that adolescents watching sexuality on television and in the media, are more likely to have sex out of curiosity. How are the levels of government working together? Each level of government support promising approaches such as abstinence education, family planning, Adolescent family life program, which was enacted in 1981 as an approach to prevent teenage pregnancy, community collaborations and youth development programs for boys and young men. All the levels of government share the same ideal goals and directives for young people. Although teenage pregnancies have decreased, it is not apparent in all regions, due to increased incidence of teenage pregnancy seen in some areas. The message is the clear ways need to be provided to help with decreasing the incidence of teenage pregnancy. Questions have been identified regarding if a 50% decrease in the 1998 levels will be met by the 2010 target date. As a way of reminding the students that abstinence is the best way to prevent pregnancy and diseases, some schools are offering the â€Å"abstinence only† education. Virginity pledges have become quite popular in this day for some young people, making a point. Conclusion Some health departments give out condoms to young women along with advice on ow to use the contraceptive. Laws against child marriage have been put into place, yet people are still marrying young people barely able to make good choices for themselves. All parents should take action by making sure that branches of government and health and education services work together, including helping them work effectively, get better support for teenage mother, including ways to obtain better education, better childcare, in addition to providing a way for them to obtain housing. Advising, counseling, and providing support can make a difference in their young lives.

The Plight of the Black Seminoles Essay examples -- American America H

The Plight of the Black Seminoles Scattered throughout the Southwest and into Northern Mexico, descendants of the Black Seminoles and Maroons are living in this modern world today. Over one hundred years ago, the U.S. government seemed determined to systematically eliminate the Native Americans and manipulate the descendants of the Black slaves. That imperialistic attitude allowed the policies of the U.S. government to treat groups of people with less respect and concern than they treated their livestock. To understand the plight of the Black Seminoles one has to look back in history to slavery days of the Southern states, and at tribal changes of the Florida Natives. At the beginning of the eighteenth century Native Americans from various groups went into Spanish Florida, establishing a new identity as Seminoles (Littlefield 7). The Seminoles broke off from the Creek tribe. The word Seminole means, "one who has camped out from the regular towns," or "runaway" (Markowitz 213)." Black slaves also fled to the open territory of Florida. The Seminoles who owned slaves did not do so in the traditional plantation style of bondage. The Blacks (who were also known as Maroons) were not subordinate to their chiefs (Laurence 30). The distinction between runaway or, slave, blurred and eventually vanished. Blacks who lived among the Seminoles were useful as interpreters because they spoke English, or some other European language, and they soon learned the Seminole Muskogean dialect. The slaves who fled to Florida as adults knew the ways of whites and could often predict behavior of a particular situation. Thus the association between Blacks and Seminoles was one of affection and mutual respect (Laurence 14). Intermarriage inevit... ...ribes, and the unfavorable conditions of the Indian Territory of Oklahoma, but they managed to survive. The fact that they were not completely eradicated and still have descendants living today is a testimony to their tenacity, bravery, and enduring strength of spirit. Works Cited Champagne,Duane.Chronology of Native North American History.Detroit,1994. Laurence,Foster.Negro-Indian Relationships in the Southeast. University of Pennsylvania,1931. Littlefield,Daniel.Africans and Seminoles from Removal to Emancipation.Westport,CT:Greenwood,1977. Markowitz,Harvey."Trail of Tears".American Indians.Pasadena, CA.Salem Press,1995. Mulroy,Kevin.Freedom on the Border.Lubbock,Tx.Texas Tech,1993. Porter,Wiggens,Kenneth.The Black Seminoles.University Press, Florida,1996. Waldman,Carl.Who Was Who in Native American History.New York, NY.Facts On File,1990.

Mine safety and environmental health challenges

1. Sketch some of the cardinal wellness and safety challenges that is faced by a excavation company you are familiar with.The industry has experienced both high effect low frequence events ( catastrophes such as Moura and Gretley ) every bit good as low frequence high events ( such as faux pass, strains and falls ) contribute to the industry ‘s high lost clip hurt rate ( LTIR ) . It has besides had its portion of occupational diseases. Historically, pneumonocosis ( lung disease caused by inspiration of mineral dust ) , asbestosis and mesothelioma have been cardinal countries of concern. Noise, quiver and weariness are issues of important wellness concerns. The direction and control of major jeopardies associated with structural prostrations, fires and detonations are cardinal safety issues of the twenty-four hours.Moura:During the past 40 old ages at that place have been three mining catastrophes in the Moura territory at a cost of 36 lives.The first occurred at Kianga Mine on 20 September 1975. Thirteen mineworkers died from an detonation which was found to hold been initiated by self-generated burning. The mine was sealed and the organic structures of the work forces were ne'er recovered.The 2nd occurred on 16 July 1986 at Moura No 4 Mine when 12 mineworkers died from an detonation idea to hold been initiated by one of two possible beginnings, viz. frictional ignition or a flame safety lamp. The organic structures of the mineworkers, in this instance, were recovered.The tierce of the catastrophes occurred on 7 August 1994 at Moura No 2 Mine. On this juncture eleven mineworkers died as a consequence of an detonation. The mine was sealed and, at this clip, the organic structures have non been recovered.2. What is the model of the mine safety statute law in your state/country?Since Australia is a federation of provinces, each province sets out its ain Torahs, which include its ain regulative criterions for occupational wellness and safety. At get downing, each province was separate and used the old wellness codifications ( i.e. , statute law ) and criterions from the British system. This system relied to a great extent upon really specific ( i.e. , Numberss based ) system which was easy to implement and simple to understand. However jobs ensured as clip and engineering progressed which led to the wellness and safety reform that began in 1972.The Current Framework for Mine Safety in Australia in 3 ways:Regulations under a general OHS Act ( VIC/SA/TAS/NT )In separate Mine Safety Acts and Regulations ( WA/QLD )In separate mine Safety Act and Regulations Subordinate to a general OHS Act ( NSW )Since Victoria is my province, the undermentioned legalization will be used under 3 chief classs given as below.Dangerous Goods ActEnvironment Protection ACTOccupational Health and Safety Regulationsa ) As per Occupational Health and Safety Regulations:Occupational Health and Safety Act 2004. Act No. 107/2004: Enabling act. Sets out the cardinal ru les, responsibilities and rights in relation to occupational wellness and safety ( OHS ) . Occupational Health and Safety Regulations 2007, Statutory Rule No. 54/2007: Specifies the manner in which a responsibility imposed by the OHS Act must be performed, or prescribe procedural or administrative affairs to back up the OHS Act ( eg requiring licenses for specific activities, the maintaining of records or giving notice ) . WorkSafe Positions: Are guidelines made under subdivision 12 of the OHS Act that province how WorkSafe will use the OHS Act or Regulations or exert discretion under a proviso of the OHS Act or Regulations. WorkSafe Positions are intended to supply certainty to duty holders and other affected partiesB ) As per Environment Protection ACT:Version No. 171, Environment Protection Act 1970, No. 8056 of 1970, Version integrating amendments as at 1 January 2010. This sets out the cardinal rules, responsibilities and rights in relation to Environment Protection Act. degree Celsius ) As per Dangerous Goods Act: This sets out the cardinal rules, responsibilities and rights in relation to Dangerous Goods Act. But here separately they all made for single classs as mentioned. Version No. 081 Dangerous Goods Act 1985 No. 10189 of 1985 Version integrating amendments as at 1 January 2010 Version No. 003 Dangerous Goods ( HCDG ) Regulations 2005 S.R. No. 96/2005 Version as at 14 March 2008 Version No. 005 Dangerous Goods ( Storage and Handling ) Regulations 2000 S.R. No. 127/2000 Version integrating amendments as at 1 January 2009 Version No. 001 Dangerous Goods ( Transport by Road or Rail ) Regulations 2008 S.R. No. 166/2008 Version as at 1 January 2009 Version No. 013 Dangerous Goods ( Explosives ) Regulations 2000 S.R. No. 61/2000 Version integrating amendments as at 1 January 20093. Robens suggested two cardinal issues were of import in accomplishing high criterions of safety.What are these two key issue?Where in the Act ( or ordinance ) are these two issues addressed in themine safety statute law of your state/country?In 1972, the British Robens study sought to modify the old codifications of pattern utilizing two base principals.The first rule recognised the demand to unite all the difference OHS Torahs under one system. It was proposed that this would be accomplished by making â€Å"general duties† into one opinion ( Robens Report, para 41 ) .The 2nd rule observed that a ego ordinance theoretical account be implemented where workers and decision makers ‘come together ‘ in order addition the criterions of wellness and safety ( Robens Report, para 41 ) .The Federal Government in 1985 passed statute law to organize the so National Occupational Health and Safety Commission ( NOHSC ) ; though , because Australia is a federation, each state/territory has to sign federal statute law in order to for the committee ( NOHSC ) to be apart of the Commonwealth and hence have any legal evidences. Each province reformed OHS Torahs, based on the Robens theoretical account and beyond. In fact, the OHS operates in a three manner system. The first is the general responsibilities which cover all employees irrespective of occupation position ( Internet Explorer, contracted or non ) and require the employee as practically possible to guarantee a safe working environment. The 2nd are the â€Å"provisions in regulations† are compulsory Torahs that are specific to each province. Finally, codifications of pattern are used as counsel which set the criterions for the general responsibility of attention. These aid in puting criterions the responsibility holder is required to place the jeopardies and buttocks and control hazards and hence helps Robens 2nd rule nevertheless there remains some critical spreads.4. What is the chief end of industrial hygiene?List the four key processes that play a function in accomplishing this end.Main end of Industrial hygiene is risk decrease and/or hazard riddance wherever possible.AnticipationRecognitionEvaluationControl of workplace e nvironmental jeopardiesSpecify the undermentioned footingsHazardHazardHazard directionHazard AppraisalProbabilityFrequencyBadnessDoseTLV-TWATLV-STELHazard: A jeopardy is any ‘thing ‘ that may do injury or hurt to a individual or belongings. Besides this is the potency of any agent or substances to do injury, normally ill-health or disease.B ) Hazard: The hazard tells how likely an accident ( An accident is any unexpected or unintended event that may do injury or hurt to a individual or belongings ) will do injury or hurt to a individual or belongings. Hazard is a map of the type of jeopardy times the sum of exposure ( Risk = Hazard x Exposure )Hazards direction: The procedure of ordaining general responsibilities of attention in order to extinguish, replacement, or cut down the likeliness of an accident ( i.e. hazard ) through technology or administrative solutions, or through using personal protection equipment ( PPE ) .Hazard Appraisal: Hazard Assessment is the procedu re by which a particular hazard is quantified or qualified in order to understand how to pull off a specific jeopardy. It is based upon the consequence that a specific jeopardy may hold, the magnitude of the jeopardy ( I, e, how terrible it may be ) , and the continuance that the jeopardy may impact a individual or belongings. The hazard appraisal helps determine how a jeopardy may be managed and how a hazard may be controlled.Probability: the likeliness for an event to happen. One of the factors that serves as the dependent variable for hazard ( I.e. Risk=Probability * Severity ) orIt is a manner of showing cognition or belief that an event will happen or has occurred. In mathematics the construct has been given an exact significance in chance theory, that is used extensively in such countries of survey as mathematics, statistics, finance, gaming, scientific discipline, and doctrine to pull decisions about the likeliness of possible events and the implicit in mechanics of complex s ystems. degree Fahrenheit ) Frequency: Frequency is the rate at which a individual may come into contact with a jeopardy over a defined length of clip. Or The figure of times that a periodic map repeats the same sequence of values during a unit fluctuation of the independent variableBadness: Badness is the magnitude, or strength, with which a risky substance is exposed to a individual. It is the dimension for sorting earnestness for Technical support issues.Dose: Is the sum of the jeopardy which we are exposed. It is defined by the concentration of the risky substance times the length of clip a individual is exposed.Dose is the construct of dosage is paramount for occupational hygiene and hazard direction. Dose refers to the sum of a substance to which we are exposed, and is a combination of the concentration of exposure and continuance of exposure. Dose= concentration*duration of exposureI ) TLV-TWA:TLV values by and large refer to a national exposure criterion for a jeopardy ( i.e. chemical, dust, or radiation ) . It is a agency of quantifying the maximal concentrations of a peculiar substance in an country over a specified length of clip, and so using it as a criterion for wellness and safety inspectors and responsibility bearers to utilize as a manner of measuring hazard. TWA is an acronym for clip leaden norm. In this instance, the continuance of contaminant exposure is expressed over an eight hr working twenty-four hours and a five twenty-four hours working hebdomad. In this manner, this exposure criterion incorporates the upper limit and minimal exposure rates a individual experiences during a regular on the job twenty-four hours. The accent of an exposure free clip is implicitly involved ( as would be the instance for noise ) so that certain organic structure thresholds are non passed.J ) TLV-STEL:STEL is an acronym for short term exposure bound. For some substances, a short term exposure criterion is needed since ague and chronic wellness affects may ensue. Alternatively of an eight hr twenty-four hours, this exposure criterion is step over no more than 15 proceedingss.6. Whatare the chief airborne contaminants/pollutants that can do health-related jobs at mine sites?The Dust and particulates ( arsenic, lead, quicksilver and etc ) ;The Toxic gase s ( C monoxide, sulfur dioxide and etc ) ;The Carcinogens ( asbestos, aromatic hydrocarbons, and etc ) ;The Flammable gases ( methane and C dioxide and etc ) ;The Radiation toxicant ( radon, U, Th and etc ) ;The Mixture of viruses and bacteriums.7. For a peculiar legal legal power ( state/country ) what are the legal demands for the concentration of the followers in the general organic structure of airing air flow ( maximal or lower limit ) ?Harmonizing to the HSISa ) Oxygen Pure O: no limitations Oxygen diflouride: TWA=.05 ppm B ) Methane ( as a gas ) Pure methane: TWA=0, STEL=0 Bromomethane: 5ppm STEL=0 degree Celsiuss ) Carbon dioxide In coal mines: TWA= 12,500 ppm STEL= 30000 ppm Regular: TWA= 5000 ppm STEL= 30,000 ppm vitamin D ) Carbon monoxide: TWA= 30 ppm STEL=0 vitamin E ) Hydrogen sulfide: TWA= 10 ppm STEL= 15ppm degree Fahrenheit ) Respirable dust ( no silicon oxide ) Coal Dust: TWA = 3 mg/ M3 STEL=0 Soapstone: TWA = 3 mg/ M3 STEL=0 Vanadium: TWA = 0.05 mg/ M3 STEL=0 Graphite: TWA = 3 mg/ M3 STEL=0 g ) Respirable dust ( with silicon oxide ) : TWA= 2 mg/m3 H ) Oxides of Nitrogen: Nitrogen Triflouride: TWA= 10 ppm STEL=0 Azotic Oxide: TWA= 25 ppm STEL=0 Azotic Oxide: TWA=25 ppm STEL=0 Nitrogen dioxide: TWA= 3ppm STEL=0 Nitrogen tetroxide: TWA= 0 STEL=08. Define Dust, list and briefly describe the general preventive steps, which can be used to command or forestall exposure to high dust exposures.Dust caused by the mechanical decomposition of stuff can be defined as a aggregation of solid atoms which:Are dispersed in a gaseous medium ( normally air )Are able to stay suspended in the air for a comparatively long clipHave a high surface country to volume ratio.So briefly, over the full scope of airborne stuffs, dust by and large has the largest atom size although it can exhibit a broad particulate scope. In general, dust can be defined an merger of assorted particulates ( solid affair ) that can divide and stay in suspension in air. Dust is by and large caused by mechanical weathering through, in the instance of mines, the usage of really big machines ( drills and crushers ) and blasts. Dust can either present an immediate jeopardy ( I, e, oculus annoyance ) or long term wellness effects ( radioactive atoms that stick to respirable dust which are later inhaled ) . Whether the effects are long term or short term, there are a figure of ways that duty callings can command or even extinguish dust. 1 ) Preventative steps ( Elimination ) :This is the best manner among all.This includes irrigating to cut down dust formation when film editing and boring ; guaranting that cutting equipment is crisp, and utilizing oils to transport mine cuts to an enclosed country.Under these conditions, â€Å"the means of control† is through riddance.A concluding piece of equipment is a unsighted hole bore bit which traps the dust generated through an enclosure.2 ) Ventilation ( Engineering ) :This is an technology agencies of control dust through a proper airing system.Here the air must be able to be strong plenty to pick up the heavy dust atoms to cut down the sum of dust concentrating in the air or on the land.Dust extraction and filtration systems that pump in the ‘dusty ‘ air, filter out the atoms and so throw out ‘cleaner ‘ air.3 ) Removal of employees ( Administrative ) :This is an administrative attack where the employees are fundamentally removed from the jeo pardy thereby extinguishing exposure.This is frequently non really practical, particularly in medium/small operations, or in rural operations where all employees are needed, or working rotary motion is non an option.4 ) Use of inhalator ( PPE ) :This is the least manner control nevertheless we have no other option.Here a worker uses a inhalator in order to filtrate out the dust, thereby understating hazard by cut downing exposure.However, many inhalators can be excessively heavy or cumbrous to cover with, particularly belowground.9. Discourse how methane is generated in mines. What are the cardinal hazards associated with methane, and how can the hazards be managed?Methane coevals in mines:This is produced by bacterial and chemical action on organic stuff and is evolved during both the formation of coal and crude oil. One of the most common strata gases. It is non toxic but is unsafe as it can organize an explosive mixture with air. A methane/air mixture normally called firedamp. Methane is normally associated with coal mines but it is besides normally found in other mines which are over or underlain by carbonous formations. Methane is retained within breaks, nothingnesss and pores within stone either as a tight gas or adsorbed on mineral surfaces. When mining disturbs the stone the gas force per unit area gradient set up between the reservoir of methane and the airing system induces flow of methane along natural or excavation induced breaks towards the gap.Key Hazard:Methane has no smell, but it is frequently accompanied by hints of heavier hydrocarbons in the paraffin series, which have a characteristic oily odor. The denseness of methane is a small over half that of air. This gives rise to the danger of methane layering in pools along the roof of belowground gaps. The perkiness of methane can besides do jobs in inclined workings. Methane Burnss in air with a pale blue fire. The explosible scope for methane in air is by and large quoted as 5-15 % with maximal explosibility at 9.8 % . The lower bound remains reasonably changeless, the upper bound reduces as the O content of air falls. To track the flammability of methane air mixtures a coward diagram as shown in figure 2 can be used. With relation to calculate 1: Figure 1: The coward diagram for methane in air.In zone A the mixture is non flammable but is likely to go so if farther methane is added.In zone B the mixture is explosive and has a lower limit nose value at 12.2 % OZones C and D illustrate mixtures that may be in certain countries.Methane beds have two chief jeopardies associated with them:Layers extend the zones within which ignitions can happenWhen an ignition occurs the methane bed acts as an effectual fuse along which the fire can propagate, sometimes taking to much larger accretions in roof pits or in the mariner.Methane and Carbon dioxide ( mixtures of the two gases ) if mixed with N will do the dangers atmosphere. Because this associated with gas effusions are:Suffocation of mineworkers by gas and dust. Compressed air line of lifes may be maintained on or shut to faces that are prone to effusions.The force of the effusion may damage equipment, doing triping that may light the extremely flammable gas/dust mixture.The sudden e nlargement of a big volume of gas can interrupt the airing system of the mine.To command and Manage:To command and pull off the hazard of Methane, foremost of all demand to cognize the beginnings and nature of methane, and how the methane is let go ofing and migrating. And so apprehension of hazards can easy take to larn of the methane hazard direction. The major systems as follows,In its of course happening province in a coal seam, firedamp does non represent an explosive hazard. However, where firedamp released from next seams meets â€Å" fresh-air † in the goaf, the firedamp is diluted and explosive mixtures ( around 5 % to 15 % methane in air ) are formed. Effective firedamp control is indispensable for safe working and involves supplying either:Face-End Ventilation and Gas Control: good designed Ventilation flow avoid the hazard of methane gas.Firedamp Drainage on Retreat Longwalls: Firedamp gaining control efficiencies on longwall faces typically lie between 60 % and 8 0 % of the entire gas on progressing faces and from 30 % to 60 % of the entire gas on retreat faces. Options and Addendums to Firedamp Drain: There are airing options applicable to some retreat longwall coalfaces which can rid of the demand for dearly-won firedamp drainage. Such methods ( eg. hemophiliac roads and sewer gate systems ) are aimed at deviating gas off from working coalfaces along paths separate from those used to serve the face. Goaf Flushing: Goaf flushing has been used for temporarily betterment of firedamp concentrations in a territory return but it is non a recommended gas control solution. The method is by and large applied to a fully-developed goaf ( Internet Explorer. where sufficient goaf has been created to organize a significant gas reservoir ) . The airing force per unit area across a territory is reduced, after work forces have been withdrawn, leting high gas concentration gas to migrate frontward into the return airway. Transport activities in the chief return may hold to be suspended. Finally, the equilibrium between gas flow into the waste and gas flow into the return is restored, the gas concentration in the territory return being at a higher concentration than earlier due to the reduced air measure. On reconstructing the original air flow, the gas is forced into the goaf, off from the face, therefore cut downing the emanation into the return until equilibrium conditions are one time once mor e obtained. This attack is non advised due to the uncontrolled release of elevated firedamp concentrations into air passages and across electrical equipment.Methane Drain: To bring forth gaseous fuel and/or to cut down methane emanations in to airing system its been used. Methane that is drained demands to be transported safely to the point of bringing, the substructure that is required to accomplish this consists of the followers: Pipe ranges, Proctors, Safety devices, Controls, Extractor pumpsOther than all above mentioned, in single states they are following up regulations and ordinances to command and pull off the hazard of Methane. Here is an illustration UK statute law provinces,Electrical power must be switched off when the general organic structure concentration of methane exceeds 1.25 % .If methane concentration exceeds 2 % forces other than those associated with bettering the airing in the country should go forth the country.10. Discourse the beginnings and hazards associa ted with arsenic, quicksilver and nitriles. How can the hazards be managed?A ) quicksilver Beginnings:Natural beginnings:VentsVolatilization from oceansErosion of natural sedimentationsHuman Activities:Estimated to be 1/3-2/3 of the entire quicksilver released into the environment.Beginnings include:Stack losingss from cinnabar roastingThe working and smelting of metalsCoal fired power workssDischarges from mines, refineries and millsCombustion of coal and municipal wastes, industrial wastes and boilersMedical waste incineratorsPesticidesOverflow from landfills/croplandsB ) quicksilver Hazards:Continuity:Can alter signifier,Can non be destroyedSolubility:Cinnabar ( HgS ) is indissoluble ( and resists enduring ) ;Liquid Hg is somewhat soluble in H2O.Bioaccumulation:Hg methylation signifiers CH3Hg+ which is easy absorbed by beings and biomagnifies from the underside to the top of the nutrient concatenationBioaccumulates ( dressed ores ) in musculus and tissue of fish and other wildlif eCH3Hg+ by and large increases by a factor of 10 or less with each measure up the nutrient concatenationC ) Arsenic Beginnings:Arsenopyrite ( FeAsS ) is the most common arsenic mineral in ores and is besides a by-product associated with Cu, gold, Ag, and lead/zinc excavation.Arsenic trioxide ( Fe2As3 ) is present in flue gases from Cu ore roastingcoal-burning power workss and incinerators besides may let go of As into ambiance.Water: mean concentration is 1 ppb, but can be & gt ; 1,000 ppb in mining countries ; As+5 most prevailing ; many compounds dissolve in H2O.D ) Arsenic Hazards:Arsenic is a human carcinogenIn worlds the primary mark variety meats are the tegument and vascular systembirds, animate beings, workss, and freshwater fish can go contaminatedToxicity in H2O is determined by H2O temperature, pH, organic content, phosphate concentration, suspended dirts, presence of oxidizers, and speciationTocopherol ) Cyanides Beginnings:Can leach from landfills and cyanide-containing route salts every bit good as to the ambiance from auto fumes ( hydrogen nitrile gas – HCN ) .Some nutrients ( Prunus dulciss and lima beans ) contain nitriles of courseIt can be produced by some bacteriums, Fungis, and algaeSpills: Cyanide and other heavy metal pollutants overflowed a dike at Baia Mare, Romania, polluting 250 stat mis of rivers, and killing 1000000s of fishMost persistent in groundwater & A ; at higher pHF ) Cyanides RisksOral lethal dosage of KCN for an grownup is 200 milligramAirborne concentrations of 270 ppm is fatalLong term exposure to lower degrees consequences in bosom strivings, take a breathing troubles, purging, blood alterations, concerns and thyroid secretory organ expansionCN does non bio-accumulate in fishG ) Cyanide hazard Control Methods:Production: Encourage responsible nitrile fabrication by buying from makers who operate in a safe and environmentally protective mode.Transportation system: Protect communities and the environment during cy anide conveyance.Managing and Storage: Protect workers and the environment during nitrile handling and storage.Operationss: Manage cyanide procedure solutions and waste watercourses to protect human wellness and the environment.Decommissioning: Protect communities and the environment from nitrile through development and execution of decommissioning programs for nitrile installations.Worker Safety: Protect workers ‘ wellness and safety from exposure to cyanideEmergency Response: Protect communities and the environment through the development of exigency response schemes and capablenesss.Training: Train workers and exigency response forces to pull off nitrile in a safe and environmentally protective mode.Daily review of leach residue storage pools and shadowings bringing grapevines ;Incident coverage and a system of exigency processs ;Systems for informations recording, rating, reading and coverage ;Procedure technician preparation and consciousness of possible nitrile related j obs, including personal safety and impacts on the environing natural environment ;systematic records direction and certification of carnal mortalities ;Integrating cyanide direction processs into the site Environmental Management Plan which is presently being updated.H ) Arsenic and quicksilver hazard control methods:The above mentioned methods are suited to follow Arsenic and quicksilver every bit good. However in practical universe, it depends upon the harmness, will change to importances of handling.11. Specify the intent of airing in belowground mines. What types of airings systems are common?The intent for airing in mines is to thin assorted signifiers of gases. These gases could be either a chemical jeopardy ( as in carbon-monoxide and dust ) or explosive physical jeopardies such as methane accretion along the roofs of mine shafts. Ventilation systems frequently come in the signifier of,fans which control air flowarrests and seals will seal escapes in peculiar to older minesDoors and air locksRegulators which is a door with an appropriate transition to keep air force per unit area gradientsAircrossings which allow suction and blowing airing systems to easy by base on balls one another and non let for cross taint12. Electrical power is normally employed in mines, what work patterns would you specify for the care of electrical equipment?Always to be Maintained, reviewed and modified mine power supply systems.Make certain Consistently inspect machineraries and carry out trials for mistakes and jeopardiesMake certain ever the electrical equipment is decently viewed, so that arrange some visible radiations near electrical equipment in belowground mines to guarantee to be seeable.Make certain while Create processs to guarantee noise and electrical jeopardies ; over electromotive forces, current ordinance, noise degre e decreases etc. , are maintained to allow legislative criterions.Without excessively much emphasis, seek to supply machinery that can be moved easy that are besides within legislative demands and can provide equal electricity Create an alternate power supply beginning in instance of machinery dislocation which allows to make care activities. For the speedy designation, install proper mine overseas telegrams with appropriate coloring materials coding system. And following safety regulations and ordinances besides makes the good work patterns for the care of electrical equipment.Failure to exert cautiousness may ensue in hurt, so cautiousness must be used when runing or mending electrical equipmentWhen executing electrical work, ever use the proper protective equipment, such as: safety spectacless, protective baseball mitts, and a decently rated metre.State ordinances, Australian Standards and company policies are designed to guard against electrical jeopardies in the excavation industry. So following up those are really indispensableWet conditions may eat metal electrical constituents and do their failure. Falling stone may damage an electrical overseas telegram or constituent. So need to avoid those sort of unsafe conditions before put ining at specific topographic points or demand to take attention to avoid those jobs.Exercise cautiousness to be used to utilize proper protective equipment when working with batteries. Because batteries could detonate and do hurt or could light and do fires.All have to be cognizant and particularly all electrician decently trained to Be watchful and knowing of the jeopardies of electricity.Make certain ever maintaining attitude tono electrical work can be performed until the electrical circuit is knocked, locked, and tagged.Always make certain the frame land is decently connected.No electrical work shall be performed except by a qualified individual. Circuit surfs and gulfs shall be marked for designation. Circuit interrupting devices or proper fuses, shall be installed to protect against short circuit and overloads.u Unpluging devices shall be locked and tagged out. All electrical equipment shall be examined, tested, decently maintained, and consequences recorded as required13. Your mine employs grapevines to convey the followers:Compressed airService H2OMethaneRun of mine drainage H2OHow would you guarantee that each grapevine can be readily identified by a speedy ocular review?C oloring the pipes with different sort of colorss may give solution to this instance. Examples:Blue coloring material for service H2ORed coloring material for Compressed airGreen coloring material for MethaneYellow coloring material for mine drainage H2OThis manner each pipe is easy visualised in the mine. A mark that demarcates the coloring material coding system will besides be necessary to clear up the coloring material cryptography system.14. Distinguish, with the usage of illustrations, the difference between major, chronic and minor incidents. What are the legal demands for describing these different types of incidents in your legal power?Incident is a happening of an event that has a non human component to it ( unlike accidents ) . Major incidents: Are sudden alterations which are dramatic, necessitate immediate responses, and are by and large dearly-won and a figure of human deaths. An illustration is methane gas effusions in belowground coal mines. Examples:Major fire, detonationFatalityStructural prostrationMajor equipment harmMajor loss of productionTypically cost 1000000s of moneysChronic Incidents: Are events that result in an hurt ; is related to a figure of causes, and have effects that are lower in magnitude and strength than major incidents. Sometimes these events may do change in the normal processs in mines. Examples:Recuring quality divergence.Recuring equipment failure.System corrosion/erosion.Fleeting emanations.Slips, trips and falls.Minor Incidents: Or near miss incidents which do non involved in any loss or hurt but if a different event occurred, could do hurt or injury. When these incidents happened, the legal demand is 5 stairss:ReportingGathering the FactsDetermine Cause ( s )Develop and Implement Corrective ActionMonitor and Review15. Discourse four theories of accident causing.1. Domino theory:It is developed by Herbert Hinrich ( Travelers Insurance Co ) in 1920.Says that hurts occur from actions that interact. The hurts are caused by insecure Acts of the Apostless by workers and are by and large preventable given proper safety preparation. It includes:Injuries arise from a set of complete actionsMost hurts arise from insecure Acts of the ApostlessAccidents are mostly preventableInsecure Acts of the Apostless can hold ulterior effects vs immediateManagement should take controlHarmonizing to Heinrich, five factors can take up to an accident:Lineage and societal environmentMistake of a individualInsecure mechanical or physical state of affairssThe accident itself ( falls, being hit )Injury: Typically lacerations and breaksUnder this rubric, direction should take control and supply safety to workers.2. Human Factors Theory:Accidents are caused by human mistake under three chief factors:Overload ( instability in a individuals capacity )Inappropriate Response: How a individual responds to a state of affairsInappropriate Activity: Human mistake in judgement, action, way, etc. )3. Accident and Incident Theory:Asper this theory, the environment is a cause alternatively of human mistake. The design and excessively high of outloo k in work end product are the causes of accidents. Therefore, there is an indirect influence of direction and economic factors ( deadlines, agenda, budget, peer force per unit area etc. ) that can take to bad judgement and therefore accidents. The Accident and Incident Theory proposes a causal relationship exists between direction clime and focal point, and accident causing.4. Epidemiologic Theory:Accidents are caused bysensitivity features ( cultural, physical charecteristics, societal norms )Situational characterisitics ( unequal preparation, small counsel, or direction â€Å"climate† ) .Under this theory there is a causing nexus between the environment and societal or mental factors. The Epidemiology theory holds that theoretical accounts used for survey and finding of disease can be utilized for accident causing as good16. ( a ) What is occupational hearing loss?A signifier of hearing loss due to the disfunction of the auditory nervus, ( i.e. hearing loss ) that is caused by the overexposure to noise degrees of high strength ) . This is besides called acoustic injury hearing loss( B ) Define the footings frequence, strength, dubnium, dubnium ( A )Frequency: The rate at which sound atoms vibrate through an elastic medium that the ear can comprehend as ‘sound ‘ .Frequency = Cycles per Second = Hertz = Hz 1000 Hz = 1 Kilohertz = 1 kilohertz = Human Voice Intensity: Intensity is the sum of energy going through a unit volume of air during a certain timeframe. dubnium: The dB ( dubnium ) is a logarithmic unit that indicates the ratio of a physical measure ( normally power or strength ) relation to a specified or implied mention degree. Amplitude = Loudness = Decibels = dubnium 60 dB = Average Speaking Voice dubnium ( A ) : It is the frequence response curve which is resembles the normal frequence hearing curve for most people. A metre utilizing this web will give a consequence which does hold some resemblance in degree to that degree which is experienced by most people The other manner we can state that, Noise is measured in dBs ( dubnium ) at a certain graduated table, such as A or C. The dB graduated table is logarithmic. That means, with a 5dB exchange rate, 95 dubnium is 100 % more noise than 90 dubnium.( degree Celsius ) Define the term Daily Noise Dose ; what factors influence this?Daily Noise Dose:The Daily Noise is an exposure criterion that measures the grade a individual working is able to be exposed to resound. Worksafe states that a degree of 85 dubnium ( S ) ( ie not additive criterion ) over 8 hr twenty-four hours ( much like the clip weight norm ( TWA ) exposure standard ) should non be breached, nor a peak degree of 140 dubniums at any specific clip should non be breached ( much like the TLV-STEL ) . If exposure to resound is to happen above these degrees a step of control upon noise is required. Harmonizing the National Institute for Occupational Safety – NIOSH – the day-to-day dosage degree – D – should non be or transcend 100. When the day-to-day noise exposure consists of periods of different noise degrees, the day-to-day dosage can be calculated as: D = ( te1 / td1 + te2 / td2 + †¦ + ten / tdn ) 100 % ( 1 ) where D = day-to-day noise exposure ( % ) Te = exposure clip at a specified noise degree td = maximal continuance clip at a specified noise degree The day-to-day dosage can be converted to an 8-hr Time-Weighted Average -TWA by the expression TWA = 10 log ( D / 100 ) + 85 ( 2 )

Z Score

MN 215 A & B October 02, 2012 Z Scores, Z Tests and t Tests Overview and Review At the beginning of the course we learned that there are two branches of statistics, namely, parametric and non-parametric. Further we learned that parametric statistical processes are broken down into two other categories, namely descriptive statistical processes and inferential. We learned also that descriptive statistics (mean, mode, median, standard deviation, and frequencies) are only to be used to describe the characteristics of the data rather than draw conclusions of make inferences from the measurement data collected.However, the importance of descriptive statistics cannot be undermined as they form the basis for the workings of inferential statistical processes – especially the mean. In data analysis one of the most important concepts to remember is that regardless of the topic or issue being investigated all is based on the mean of a data set. Although we cannot draw conclusion or make p redictions from descriptive statistics their usefulness in inferential statistics is significant.As stated inferential statistics is a branch of statistics that is used in making inferences about traits or characteristics of a greater population on the basis of sample measurement data. The primary goal of inferential statistics is to leap beyond the measurement data at hand and make inferences about a greater population. Take for example a psychologist who is interested in knowing whether a new behavior modification product will likely be a seller in a certain market area.Knowing that the entire consumer population cannot be queried as to market acceptance, the psychologist would select a representative sample for the area, administer whatever measurement instrument is necessary to garner the data and, on the basis, of the sample data results, determine whether or not the new product will be profitable. The statistic used to determine whether or not the sample is representative of t he entire market population would be an inferential statistics.When using inferential statistical processes to generate information in order to make predictions about a larger population the chosen sample must always be on the basis of random selection or random assignment. Without random sampling or random assignment the mathematical values received by way of the statistical analysis are in err. Or, another way of putting is to say that the results would be â€Å"Lies, damn lies† about the data analyzed. For convenience purposes throughout the remainder of this course the following symbols will be used most extensively.Statisticians, regardless of area, use English letters to denote sample statistics and Greek letters to symbolize population parameters. NameSample StatisticPopulation Parameter _ MeanX  µ (mu) VarianceSD? ? 2 (sigma squared) Standard DeviationSD ? (sigma) Correlationr ? (rho) Proportionp ? (pi) Regression Coefficient b ? ( beta)? ? When trying to arrive at conclusions that extend from the measurement data alone, inferential statistics are the data analysis tools of choice.For example, inferential statistics are used to infer from the sample data to the larger population data or when there is an need to make judgments of the probability that an â€Å"observed† difference between groups is an accurate and dependable one and not those that happened by chance alone. In order too accomplish that which inferential statistics were designed two models are available: estimation testing and hypothesis testing. In the estimation model the sample measurement data is used to estimate a parameter (population) and a confidence interval about the estimate is created.The confidence interval is basically the range of values that has a high likelihood of containing the parameter. The parameter is a numerical value that measures some part or the population measurement scores or values. The second use of inferential statistical processes is in hypo thesis testing. The most common manner in which a hypothesis is tested is by developing what is commonly called a â€Å"straw man† which is what a null hypothesis is call when looking at a situation where in the research investigator wants to determine if the data collected and analyzed is strong enough to reject the null or â€Å"straw man† hypothesis.Always remember that a null hypothesis is stated that no differences, effects or relationships will occur between and or amongst the events, occurrences, phenomenon, items, or situations being evaluated and measured as a result of some variable. A simple example of a business null hypothesis would be something like the following: There exists no statistically significant difference between widgets made of alloy A and those made of Alloy B in terms of tinsel strength acceptability. Data Requirements When Using Inferential Statistics.Thinking back to the first part of the course we learned that statistical processes must u se certain forms of numeric measurement data and this data is expressed as nominal, ordinal, interval and ratio. For descriptive statistics (frequencies and measures of central tendency) it is nominal data that is used. For inferential statistics the measurement data types to be used are either interval or ratio. However, in the social sciences and business arenas ordinal data is often times treated like interval. This is particularly true when studies attempt to assess situations by way of a Lickert scale.For convenience and review the scale presented below will help to clarify the differences between the four scales of measurement discussed earlier in the course. Indications Indicated Direction ofIndicates Amount of Absolute Difference Difference Difference Zero NominalX OrdinalX X IntervalX X X RatioX X X On the basis of the information contained in the table above the following two conditions apply when using inferential statistical processes: * Participants selected for partici pation in a study should be selected randomly. If sampling is not random, then biases occur and contaminate the accuracy of the findings. The most commonly used inferential statistics that behavioral research uses are those statistical processes that provide for the determination of relationships (correlations), differences and effects between and amongst that which is being measured or evaluated. The specific tests used are the Pearson Correlation Coefficient, Chi Square, Student â€Å"t† Test, ANOVA (Analysis of Variance), and regression. All of these techniques not only require the use of a null hypothesis but independent and dependent variables as well. Z ScoresCalculating the Z Score for Research Purposes. One of the most often used statistical processes in the behavioral sciences is the Z Score. What a Z Score accomplishes is in taking a raw measurement value or score and transforms it into a standard form which then provides a more meaningful description of the individ ual scores within the distribution. This transformation is based on knowledge about the population's mean and standard deviation. Take for example an educational psychologist who is interested in determining how individual students are comparing to the overall group of students with respect to grades.As we have learned before raw scores alone cannot provide insightful information to the psychologist how well an individual student is performing. However, what the psychologist can easily do is calculate a Z Score for each student and determine whether or not an individual student is functioning above or below the mean grade of all students together. When determining the placement of each individual, the Z Score permits the psychologist to calculate how many standard deviations, or the distance, each student is above or below the mean grade of all students together.If there is an academic standard the psychologist is using as a comparative base a different statistical formula is used c ompared to the formula needed when comparing individual performance to a local sample of student. The formulas for each are presented below. Comparing Individual to Population Standard Comparing Individual to Sample Standard The construction of the two formulas is the same with the exception that one uses the mean and standard deviation of a population and the other of a sample.What is very important to remember, especially for the psychologist, is that comparing an individual to a local academic setting may have entirely different results when the same student is compared to the industry standard. Although this might appear to be a dilemma, it is actually a possible â€Å"blessing in disguise†. Take for example the same psychologist compares all his students’ rate of academic success in a local facility and determines they are all functioning well above average, or above the mean, in their grades.What happens if the same students are compared to an academic standard a nd the results show their grade is well below the industry standard or population mean? The conclusion drawn is, therefore, that the students, although having grades are not in line with other educational facilities and corrective programming to increase the performance rate must ensue. For ease of understanding let us look at a business situation. Example. Suppose an employee is producing 3. 5 widgets per hour and the sample average number of widgets per hour is 2. 3 with a standard deviation of 0. 33. The Z Score would be calculated as follows: X = raw score X bar = mean s = standard deviation From this we can conclude that the employee’s widget production rate per hour of 3. 5 lays 1. 73 standard deviations above the mean. We can conclude further that this employee is function above the mean all others together on the production line in terms of widget production and that the employee is doing better than 95% of the other employees and only 5% of the total employees are pr oducing more widgets.NOTE: The percentages are easily found on the back of the very last page of your text book. As stated earlier caution must be exercised when drawing conclusions about a single business sample as the statistical information garnered might not be representative of industry standards. Looking at the same employee on an industry standard basis the information might possibly be different. Taking the same employee with an average widget production rate of 3. 5 widgets per hour with a hypothetical population or industry standard mean of 4. 9 and a population standard deviation of 1. 15 the results would be as follows using the formula stated above: X = Employee raw production score  µ = Population standard mean ? = Population standard deviation Z = (3. 5 – 4. 79) / 1. 15 = -1. 12 What can be readily seen by way of the negative value Z Score is that the employee falls below the standard industry mean with respect to the number of widgets produced in one hour. C oncluding further we can say that this employee standing is surpassed by 64% of the entire population workforce for he company. Needless to say, the manager needs to take a serious look at the quality of workers in his/her plant. Interpreting the Z Score for Research Purposes. When using Standard Z Scores one must always remember that comparisons are made between individual measurement values and sample or population mean values. At no time can a one use Z Score values to make predictions or drawn inferences about any given situation. To accomplish this, inferential statistical processes must be used.The value of the Z Score lies in the idea that individual tracking is necessary and trends can be plotted. Also, one must always keep in mind that X values do not have to be simple individual raw scores but can also reflect any investigative variable the researcher chooses to investigate. â€Å"Z† Test When to use the Z Test over the â€Å"t† Test in Research. Although bot h the Z test and the â€Å"t† test are used in research decision hypothesis testing each is used under a different set of circumstances than the other. The primary distinction between the two lies in the sample size requirement.Where â€Å"t† tests can be used for small samples the Z Test cannot and is, therefore, reserved for sample situations that are larger. Both, however, perform the same function, namely to determine whether or not there are differences between the samples being evaluated or comparisons between sample and population measurements. In addition both the Z and â€Å"t† tests make use of the mean scores for raw measurement data when calculating differences. Presented below are some examples of using both the Z test and â€Å"t† test in business today. Z Test: A product safety engineer wants to investigate the average number of possible defective products in worldwide production. A sample is drawn sample (in excess of 30) and mean of the s ample is compared to the population mean for evaluation. * Z Test: A psychologist wants to investigate whether or not a 10 hour shift will record more safety accidents in product production compared to the company wide population standard of eight hour shifts. * Z Test: A human resource manager wants to investigate whether or not a new employee training program will increase production numbers company wide. â€Å"t† Test: A psychologist wants to investigate whether or not the sample of 20 line employees of plant A are producing a significantly greater number of products than the sample of 20 employees of plant A. * â€Å"t† Test: A consumer product safety manager wants to investigate whether or not his small firm is producing an equal number of safe products compared to the industry standard. * â€Å"t† Test: A human resource manager is interested in knowing if customer service skills of employees in department A are the same as in department B.What is most impo rtant to remember is that both the t and Z tests are formulated to arrive at the same conclusion but under different sampling conditions. Keep in mind as well that the Z test is used when the population mean is known. In addition when using a â€Å"t† test with a small sample base it is assumed the distribution of the data is normal; however, in larger samples the distribution does not have to be normal and a Z test can be used for comparative purposes. Further, in both situations the samples drawn must be on a random basis.The unfortunate limitation of both tests is in the fact that neither permit any conclusions to be drawn if not differences are found between the sample means or sample and population mean. However, one must always keep in mind that Z and â€Å"t† tests are basically the same as they compare two means to determine whether or not both samples come from the same population. Calculating the Z Test. The example presented below not only provides you with a formula for both population mean testing but sample mean testing as well.What must be closely watched is the effect on sample size with respect to any resulting Z value: Remember that the Z test requires a large sample and should a small sample be used the resulting Z value is contaminated. Formula: Sample vs. PopulationSample vs. Sample __ __ __ Z = / Z = X1 – X2 N 2(1/N + 1/N) Example Sample vs. Population:Suppose a product manager is interested in knowing if the number of faulty washing machines being produced in his/her plant in August is indicative of the over-all number of washing machines produced in all plants during the month of August. The product manager draws two samples from his/her assembly line: a sample of 10 and a sample of 100. The example being created is to show how the size of the sample bears directly on the resulting Z Test value. Formula: __ _ Z = / N Data.Sample Test Mean = 30 Population Mean = 25 (Industry Requirement) Population = 15 N = 10 __ Z = / N = 30-25 / 15 / 3. 16 = 15 / 4. 75 Z = 1. 58 Sample Test Mean = 30 Population Mean = 25 (Industry Requirement) Population = 15 N = 100 _ Z = / N = 30-25 / 15 / 10 = 5 / 1. 5 Z = 3. 33 Conclusion: The conclusion the production manager can draw from the above measurement example (N=10 and N=100) is relative to the size of the sample used to determine whether or not the sample is representative of the overall faulty washing machine production in August.Had the production manager set the level of confidence at 0. 01 (99%) the Z test score needed in order to reject the null hypothesis that no differences exist in washing machine production is +1. 96. A Z test value for the 10 sample situation of +1. 58 does not meet or exceed the required value of +1. 96. Therefore, the production manager concludes there is not statistically significant difference in the August faulty washing machine production rate for his/her plant and the overall faulty washing machine production rate of all plan ts.However, when the sample size is increased the resulting Z test value is extremely different. The 100 sample case, using the same values as in the 10 sample case, provides an entirely different scenario. By increasing the sample size tenfold the resulting Z test value is +3. 33. Obviously this numeric value far exceeds the required +1. 96 value and the production manager can safely conclude that statistically significant differences exist between the faulty washing machine productions in the production manager’s plant compared to the average faulty washing machine production rate of all plants.The reason for the difference in Z test values in knowing that as sample size increases so does the Z test value. Although not shown in this example, but also extremely important, is in knowing that when the variance of the sample differs from the population variance there will exist a lower Z test value. In the 100 sample test, should the resulting Z test value not met the required 1. 96 value the production manager could have concluded that the faulty washing machine production rate of his/her plant meets the production rate of all other plants together for the month of August.As scientific research and applied statistics application are not equipped to lend explanation as to why no differences are determined the only conclusion to be drawn is that the lack of differences is a direct result of sample size and variance. Example Sample vs. Sample vs. Sample Formula: __ __ Z = X1 – X2 2(1/N + 1/N) Example: Suppose the same product manager is interested in knowing if the number of faulty washing machines being produced in his/her plant in August is indicative of the number of faulty washing machines produced in a neighboring plant during the month of August.The product manager draws two samples: one from his/her assembly line and one from the neighboring plant: a sample of 100 is drawn from both plants. _ Data: : Sample 1: N=100 X=30 _ Sample 2: N=100 X=25 = 15 (known or assumed) _ _ Z = X1 – X2 2(1/N + 1/N) = 30 – 25 / (15)? (1/100 + 1/100) = 5 / v (225) (. 01 + . 01) = 5 / 4. 5 = 5 / 2. 12 = 2. 35 Conclusion: On the basis of the Z test value above the production manager would have to conclude that there exists a statistically significant difference in the production rate of the two plants at the . 1 confidence level (99%) as the required critical value of 1. 96 was matched and exceeded. As such it can be stated that the two washing machine samples are not representative of each other and differences occur. Should the product manager replicate the study and use only 10 washing machines per sample the resulting Z test value would be 1. 11 and the conclusion drawn would be that no statistically significant differences are present between the two groups and the population.Again this is an example of how sensitive the Z test is to sample size. One must always keep in mind that re-testing a product or service with artificia l conveyances (smaller sample size) in order to show that differences are not present is scientifically and professionally unacceptable. Research results must be allowed to fall wherein the statistical analysis places them. Doing otherwise is using the statistical process for reasons other than that which they were intended Drawing Conclusions from the Z Test.Business situations are not unlike any other professional situation, including the behavioral sciences, wherein the researcher or investigator is seeking information as to possible differences between samples or sample and the general population. When business managers or psychologists at any level are interested in making comparisons between products and or services the best-fit statistical tool for large sample situations is the Z test. However, the statistical value is only as good as the controls placed on it and at no time will the actual values give a reason as to why something has happened or why something has not.With r egard to the utilization of the Z test in business decision-making the following rules are always to be remembered: * Z Tests can be used to compare a sample to a population or sample to a sample for general population inference. * Z Tests are extremely susceptible to size of sample and variance and not useful when population variance is unknown. * Z Tests work best with very large samples but not with small samples as the correction factor cannot accommodate for the error associated with small samples. Z Tests are natural introductions to t Tests. * Z Tests work with only one (1) dependent variable. * Z Tests cannot work with correlated data. * Z Tests do not permit the making of strong inferences about differences or effects of the testing instrument or situation. * Z Tests have a non-parametric counterpart wherein small samples can be used. â€Å"t† Test 1a. Introduction to Difference Testing. Difference testing is used primarily to identify if there is a detectable differ ence between products, services, people, or situations.These tests are often conducted in business situations to: * Ensure a change in formulation or production introduces no significant change in the end product or service. * Substantiate a claim of a new or improved product or service * Confirm that a new ingredient/supplier does not affect the perceived attributes of the product or service. * Track changes during shelf-life of a product or the length of time of a service. Differences Between Two Independent Sample Means: Coke vs. Pepsi. Let us again look at a business example wherein the independent sample t-tests are sed to compare the means of two independently sampled groups. Example: do those drinking Coke differ on a performance variable (i. e. numbers of cans consumed in one week) compared to those drinking Pepsi. The individuals are randomly assigned to the Coke and Pepsi groups. With a confidence interval or ?. 05 (corresponding probability level of 95 %) the researcher c oncludes the two groups are significantly different in their means (average consumption rate of Coke and Pepsi over a one week period of time) if the t test value meets or exceeds the required value.If the t value does not meet the critical t value required then the research investigator simply concludes that no differences exist. Further explanation is not required. Presented below is a more useable situation. Example: As a manager of production let us suppose you are wanting to determine whether or not work performance is significantly (statistically) different in a noise related production line vs. a non-noise related production line. Individual Noise Production Non-Noise Production difference: 1-2 38 32 6 2 10 16 -6 3 84 57 27 4 36 28 8 5 50 55 -5 6 35 12 23 7 73 61 12 8 48 29 19 Mean 46. 8 36. 2 10. 5 Standard dev 23 19 12 Variance 529 361 N = 16 Using the raw data and formula above to calculate the t test value the actual t test value, when calculated properly, is 2. 43 . Always remember that S = Standard deviation and that the mean is often times shown by the capital letter M rather than a bar mark over a capital X.By going to the appropriate t tables in your text book find the critical value for t at the . 05 confidence interval. The value you should find is 1. 761 Differences Between Two Means of Correlated Samples: Red Bull vs. Power Drink. Again using a business example correlated t test statistical processes are used to determine whether or not there is a relationship of a particular measurement variable on a pre and post test basis. Often times when there exists a statistically significant relationship on a pre and post test basis the business manager can use the first measurement values to predict the second in future situations without having to present a post test situation.Example: Using the same data presented above let us assume that there are not two independent groups but the same group under two different conditions – noise p roduction environment and non-noise production environment. Individual Noise Production Non-Noise Production difference: 1-2 1 38 32 6 2 10 16 -6 3 84 57 27 4 36 28 8 5 50 55 -5 6 35 2 23 7 73 61 12 8 48 29 19 N = 8 The first step is to compute the mean of the differences: _ D = ? D N The second step is to square the differences: (6)? + (-6)? + (27)? + (8)? + (5)? + (23)? + (12)? + (19)? The third step is to calculate the standard error of the difference: SED = _ ?D – D? / n -1 n The last step is to compute the t test value: _ t = D / SED Using the raw data and formula above to calculate the t test value the actual t test value, when calculated properly, is 3. 087. By going to the appropriate t tables in your text book you can find the critical value to be, at the ? .05 confidence interval is 1. 895.The conclusion drawn is that the differences are statistically significantly different. When to Use Independent Mean or Correlated Sample Difference Testing. In research inv estigation situations the choice of using an independent sample t test of a correlated sample test is dependent upon whether or not the investigator is seeking to determine differences or relationships. In some situations the need to know whether or not a difference exists between two products or services is more important than knowing if there is a relationship between the two. For example: take the consulting psychologist wants to know if training program A has better success in training managers than training method B.The psychologist would select a sample of each training situations (generally ;30) and test the success of each sample and compare the success of program A with program B. The results would confirm if one training programs was better that the other. If, however, the psychologist was interested in determining how each program compared to the industry standard the programs would be compared, independently, to the population program mean. On the other hand should the c onsulting psychologist wants to determine whether or not a relationship exists, or predictability can be determine, from one program in two different situations or under two different situations a correlated t test is used.However, knowing the relationship in pre and post test situations are generally reserved for improvement situations. Drawing Conclusions for the t Test. Any conclusion drawn for the t test statistical is only as good as the research question asked and the null hypothesis formulated. â€Å"t† tests are only used for two sample groups, either on a pre post-test basis or between two samples (independent or dependent). The t test is optimized to deal with small sample numbers which is often the case with behavioral scientists in any venue. When samples are excessively large the t test becomes difficult to manage due to the mathematical calculations involved.