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1、CHAPTER 1:A Preview of Business Statisticsto accompanyIntroduction to Business Statisticsfourth edition, by Ronald M. WeiersPresentation by Raymond 2002 The Wadsworth GroupChapter 1 - Key TermsCollection, summarization, analysis, and reporting of numerical findingsYesterdayCounting people or possess
2、ions to facilitate taxationTodayStatistics and its applications are an integral part of our lives 2002 The Wadsworth GroupChapter 1 - Key TermsDescriptive versus inferential statistics1. Descriptive statisticsSimply summarize and describe data2. Inferential statistics (Inductive statistics)Go beyond
3、 mere description of the data and arrive at inferences regarding the phenomena or phenomenon 2002 The Wadsworth GroupChapter 1 - Key TermslDescriptive StatisticsDuring 2000,members of Congress received a total of 80 million e-mail messages, more than double the number received during 1998More than 1
4、800 plants and animals are on the U.S. Department of the Interiorss list of endangered speciesDuring Jan 2001, 80.6% of Continental Airlines flights arrived on timeChapter 1 - Key TermslInferential StatisticsResearch by Nielsen estimates that 162.8 million American have web access at homeOf 1400 cor
5、porate chief financial officers surveyed, 38% said “frequent recognition of accomplishments” was the best way to motivate their employeesChapter 1 - Key TermsInferential StatisticsEx 1:Ex 1: (Selvanathan, p.8, ex.1.3 (2000 edition p.7, ex. 1.3) (Selvanathan, p.8, ex.1.3 (2000 edition p.7, ex. 1.3)A
6、councillor who is running for the office of mayor of a city with 25 000 A councillor who is running for the office of mayor of a city with 25 000 registered voters commissions a survey. In the survey, 48% of the 200 registered voters commissions a survey. In the survey, 48% of the 200 registered vot
7、ers interviewed say they planned to vote for her.registered voters interviewed say they planned to vote for her.a)a)What is the population of interest?What is the population of interest?The intentions of the 25 000 registered voters to vote for her or not.The intentions of the 25 000 registered vote
8、rs to vote for her or not.b)b)What is the sample?What is the sample?The intentions of the 200 selected registered voters.The intentions of the 200 selected registered voters.c)c)Is the value 48% a parameter or a statistic?Is the value 48% a parameter or a statistic?It is a statistic, since it refers
9、 to the proportion of registered voters in the It is a statistic, since it refers to the proportion of registered voters in the sample who intend to vote for this politician.sample who intend to vote for this politician.Ex 2:Ex 2: (Selvanathan, p.8, ex.1.6 (2000 edition p.7, ex. 1.6) (Selvanathan, p
10、.8, ex.1.6 (2000 edition p.7, ex. 1.6)You are shown a coin that its owner says is fair in the sense that it will You are shown a coin that its owner says is fair in the sense that it will produce the same number of heads and tails when flipped repeatedly.produce the same number of heads and tails wh
11、en flipped repeatedly.a)a)Describe an experiment to test this claim.Describe an experiment to test this claim.Flip the coin, e.g. 30 times, and observe the outcomes (H or T).Flip the coin, e.g. 30 times, and observe the outcomes (H or T).The claim is false, if H (or T) is not produced exactly 50% of
12、 the trials.The claim is false, if H (or T) is not produced exactly 50% of the trials.b)b)What is the population in your experiment?What is the population in your experiment?The set of outcomes (H or T) of large number (e.g. 10 000) of possible The set of outcomes (H or T) of large number (e.g. 10 0
13、00) of possible trials.trials.c)c)What is the sample?What is the sample?The set of outcomes (H or T) of the 30 trials actually performed.The set of outcomes (H or T) of the 30 trials actually performed.d)d)What is the parameter?What is the parameter?The proportion of H (or T) in the population.The p
14、roportion of H (or T) in the population.e)e)What is the statistic?What is the statistic?The proportion of H (or T) in the sample.The proportion of H (or T) in the sample.Chapter 1 - Key TermsInferential StatisticslStatisticMeanMedianModeProportionRangeStandard deviationMeasure of Typicalness orCentr
15、al TendencyMeasure of Spread or DispersionParameterQuestions?lWhat is the difference between description statistics and inferential statistics? Which branch is involved when a state senator surveys some of her constituents in order to obtain guidance on how she should vote on a piece of legislation?
16、Questions?lIn 1995, the Cinergy Corporation sold 43,153 million cubic feet of gas to residential customers, an increase of 10.5% over the previous year. Does this information represent descriptive statistics or inferential statistics? Why?Types of VariablesQualitative VariablesAttributes, categories
17、Examples: male/female, registered to vote/not, ethnicity, eye color.Quantitative VariablesDiscrete - usually take on integer values but can take on fractions when variable allows - counts, how manyContinuous - can take on any value at any point along an interval - measurements, how much 2002 The Wad
18、sworth GroupTYPES OF DATATYPES OF DATA Qualitative:Qualitative:Data which indicate the category or group that anData which indicate the category or group that anobject or item is in. object or item is in. Not measurable (e.g. gender of students). These Not measurable (e.g. gender of students). These
19、 are nominal qualitative data. Occasionally the categories can be ranked are nominal qualitative data. Occasionally the categories can be ranked ( (egeg. . BBusBBus, Hon, , Hon, MasMas, , PhdPhd). These are ordinal data.). These are ordinal data. Quantitative:Quantitative:Data which arise from a cou
20、nting or measuring Data which arise from a counting or measuring activity. activity. Numerical observations, (e.g. exam results). Numerical observations, (e.g. exam results). Data measured in real numbers are interval data.Data measured in real numbers are interval data.Continuous quantitativeContin
21、uous quantitative: (e.g. height, length, duration, volume). : (e.g. height, length, duration, volume). Data can assume an infinite set of values within a Data can assume an infinite set of values within a given interval. Eg. 2.5 is within the interval 2.49 given interval. Eg. 2.5 is within the inter
22、val 2.49 and 2.51. So are 2.501 and 2.5011. and 2.51. So are 2.501 and 2.5011. The possible The possible values are too many to be listed or counted, values are too many to be listed or counted, hence the term continuous.hence the term continuous. B Basic arithmetic operations (+, , x, asic arithmet
23、ic operations (+, , x, ) make sense.) make sense.Discrete quantitative: Discrete quantitative: Data measured in whole numbers. Data measured in whole numbers. The possible The possible values can be listed and counted.(eg. number of values can be listed and counted.(eg. number of students in differe
24、nt tutorial classes).students in different tutorial classes).Ex 3:Ex 3: (Selvanathan, p.23, ex.2.4 (2000 edition p.16, ex. 2.4) (Selvanathan, p.23, ex.2.4 (2000 edition p.16, ex. 2.4)Information concerning a magazines readership is of interest both to Information concerning a magazines readership is
25、 of interest both to the publisher and to the magazines advertisers. A survey of 20 the publisher and to the magazines advertisers. A survey of 20 subscribers included the following questions. For each, determine the subscribers included the following questions. For each, determine the data type of
26、possible responses.data type of possible responses.a)a)What is your age?What is your age?Quantitative, theoretically continuous, but discrete in practice.Quantitative, theoretically continuous, but discrete in practice.b)b)What is your sex?What is your sex?Qualitative.Qualitative.c)c)What is your ma
27、rital status?What is your marital status?Qualitative.Qualitative.Qualitative, ranked.Qualitative, ranked.e)e)How many other magazines do you subscribe to?How many other magazines do you subscribe to?Quantitative, discrete.Quantitative, discrete.d)d)Is your annual income less than $20 000, between $2
28、0 000 andIs your annual income less than $20 000, between $20 000 and40 000, or over $40 000?40 000, or over $40 000?Data can also be classified asData can also be classified as Cross-sectional data:Cross-sectional data: All observations are collected at a single point in time,All observations are c
29、ollected at a single point in time,but they represent different entities. (E.g. GDPs of OECD countries in 2000.)but they represent different entities. (E.g. GDPs of OECD countries in 2000.)Time-series data:Time-series data: The observations are collected at regular intervals of time,The observations
30、 are collected at regular intervals of time,but they represent a single entity. (E.g. GDP of Australia from 1960 to 2000.)but they represent a single entity. (E.g. GDP of Australia from 1960 to 2000.) Statistical data is usually stored in a computer file (eg.Statistical data is usually stored in a c
31、omputer file (eg.spreadsheetsspreadsheets). ). Case: Case: AllAll responses from a person in a sample or census responses from a person in a sample or census. .Each row in the spreadsheet is a case. Each row in the spreadsheet is a case. (E(E.g. The answers to all .g. The answers to all questions on
32、 a questionnaire filled in by one respondentquestions on a questionnaire filled in by one respondent.) .) Variable: Variable: All All responses responses to a particular question to a particular question in a sample orin a sample or censuscensus. . Each Each column column in the spreadsheet is a in
33、the spreadsheet is a variablevariable. . (E(E.g. The answers to .g. The answers to a a particular particular question on a questionnairequestion on a questionnaire filled in by filled in by allall respondent respondents)s)For each of the following, indicate whether the appropriate variable would be
34、qualitative or quantitative. If the variable is quantitative, indicate whether it would be discrete or continuous. 2002 The Wadsworth Groupa) Whether you own an RCA Colortrak television setb) Your status as a full-time or a part-time studentc) Number of people who attended your schools graduation la
35、st yearQualitative Variabletwo levels: yes/nono measurementQualitative Variabletwo levels: full/partno measurementQuantitative, Discrete Variablea countable numberonly whole numbers 2002 The Wadsworth GroupProblem 1.16, continuedd) The price of your most recent haircute) Sams travel time from his do
36、rm to the Student UnionQuantitative, Discrete Variablea countable numberonly whole numbersQuantitative, Continuous Variableany numbertime is measuredcan take on any value greater than zero 2002 The Wadsworth GroupProblem 1.16, continuedf) The number of students on campus who belong to a social frate
37、rnity or sororityQuantitative, Discrete Variablea countable numberonly whole numbers 2002 The Wadsworth GroupQuestions?lWhat is the difference between a qualitative variable and a quantitative variable? When would each be appropriate?lWhat is the difference between discrete and continuous variables?
38、 Under what circumstances would each be applicable?Scales of Measurement The process of assigning a numerical value to a variable is called measurement.Nominal Scale - Labels represent various levels of a categorical variable.Ordinal Scale - Labels represent an order that indicates either preference
39、 or ranking.Interval Scale - Numerical labels indicate order and distance between elements. There is no absolute zero and multiples of measures are not meaningful.Ratio Scale - Numerical labels indicate order and distance between elements. There is an absolute zero and multiples of measures are mean
40、ingful. 2002 The Wadsworth GroupBill scored 1200 on the Scholastic Aptitude Test and entered college as a physics major. As a freshman, he changed to business because he thought it was more interesting. Because he made the deans list last semester, his parents gave him $30 to buy a new Casio calcula
41、tor. 2002 The Wadsworth GroupExample: Scales of MeasurementProblem 1.20,continuedIdentify at least one piece of information in the:a.Nominal scale of measurementb.Ordinal scale of measurementc.Interval scale of measurementd.Ration scale of measurementProblem 1.20, continueda) nominal scale of measur
42、ement.1. Bill is going to college.2. Bill will buy a Casio calculator.3. Bill was a physics major.4. Bill is a business major.5. Bill was on the deans list. 2002 The Wadsworth GroupProblem 1.20, continuedb) ordinal scale of measurementc) interval scale of measurementd) ratio scale of measurementBill
43、 is a freshman.Bill earned a 1200 on the SAT.Bills parents gave him $30. 2002 The Wadsworth GroupStatistics In Business DecisionslDecision makingPlant expansionsNew product developmentPersonnel selectionQuality assuranceProduction techniquesSupplier choicesStatistics In Business Decisions，continuedl
44、Research processDefining the problem in specific terms Deciding on the type of data requiredDetermining through what means the data will be obtainedPlanning for the collection of data and ,if necessary, selection of a sampleCollecting and analyzing the dataDrawing conclusions and reporting the findi
45、ngsFollowing through with decisions that take the finding into considerationExerciseslA research firm observes that men are twice as likely as women to watch the Super Bowl on TV. Does this inform-ation represent descriptive statistics or inferential statistics? Why?lFor each of the following, indic
46、ate the scale of measurement that best describes the information.Exercises ,continued1.On Dec 31,1995, Bausch & Lomb, Inc. had approximately 14,000 employees.2.USA Today reports that the previous days highest temperature in the United States was 113 degrees in Death Valley, California.3.An individual respondent answers “yes” when asked if TV contributes to violence in the United States.4.In a comparison test of three performance auto, Car and Driver magazine gives the highest rating to the Audi A4 Quattro, with the BMW 328i and the Saab 900SE Turbo coming in second and third, respectively
