chap4-a

Embed Size (px)

Citation preview

  • 7/30/2019 chap4-a

    1/57

    11SlideSlide

    Business Statistics (BUSA 3101)Business Statistics (BUSA 3101)

    Dr.Dr. LariLari H.H. [email protected]@clayton.edu

  • 7/30/2019 chap4-a

    2/57

    22SlideSlide

    Chapter 4 (Part A)Chapter 4 (Part A)

    Descriptive Statistics: Numerical MeasuresDescriptive Statistics: Numerical Measures

    Measures of LocationMeasures of Location

    Measures of VariabilityMeasures of VariabilityNumerical Data

    Properties

    Mean

    Median

    Mode

    Midrange

    Midhinge

    CentralTendency

    Range

    InterquartileRange

    Variance

    Standard Deviation

    Coeff. of Variation

    Variation

    Skew

    Kurtosis

    Shape

    Numerical DataProperties

    Mean

    Median

    Mode

    Midrange

    Midhinge

    CentralTendency

    Range

    InterquartileRange

    Variance

    Standard Deviation

    Coeff. of Variation

    Variation

    Skew

    Kurtosis

    Shape

  • 7/30/2019 chap4-a

    3/57

    33SlideSlide

    Measures of LocationMeasures of Location

    If the measures are computedIf the measures are computedfor data from a sample,for data from a sample,

    they are calledthey are called sample statisticssample statistics..

    If the measures are computedIf the measures are computed

    for data from a population,for data from a population,they are calledthey are called population parameterspopulation parameters..

    A sample statistic is referred toA sample statistic is referred toas theas the point estimatorpoint estimator

    of theof the

    corresponding population parameter.corresponding population parameter.For example,For example,

    thethe

    sample mean is asample mean is a

    point estimator of the population mean.point estimator of the population mean.

    MeanMean

    MedianMedian

    ModeMode

    PercentilesPercentiles

    QuartilesQuartiles

  • 7/30/2019 chap4-a

    4/57

    44SlideSlide

    MeanMean

    TheThe

    meanmean

    of a data set is the average of all the dataof a data set is the average of all the data

    values.values.

    As we said, the sample mean is the point estimatorAs we said, the sample mean is the point estimator

    of the population meanof the population mean ..xx

  • 7/30/2019 chap4-a

    5/57

    55SlideSlide

    Sample MeanSample Mean xx

    Number of

    observationsin the sample

    Number ofNumber of

    observationsobservationsin the samplein the sample

    Sum of the valuesof the n

    observations

    Sum of the valuesSum of the valuesof theof the nn

    observationsobservations

    ixx

    n

    ix

    x

    n

  • 7/30/2019 chap4-a

    6/5766SlideSlide

    Population MeanPopulation Mean

    Number of

    observations inthe population

    Number ofNumber of

    observations inobservations inthe populationthe population

    Sum of the valuesof the N

    observations

    Sum of the valuesSum of the valuesof theof the NN

    observationsobservations

    ix

    N

    ix

    N

  • 7/30/2019 chap4-a

    7/5777SlideSlide

    Seventy efficiency apartmentsSeventy efficiency apartments

    were randomly sampled inwere randomly sampled ina small college town. Thea small college town. The

    monthly rent prices formonthly rent prices for

    these apartments are listedthese apartments are listedin ascending order on the next slide.in ascending order on the next slide.

    Sample MeanSample Mean

    Example:Example:

    Apartment RentsApartment Rents

  • 7/30/2019 chap4-a

    8/5788SlideSlide

    425 430 430 435 435 435 435 435 440 440

    440 440 440 445 445 445 445 445 450 450

    450 450 450 450 450 460 460 460 465 465

    465 470 470 472 475 475 475 480 480 480

    480 485 490 490 490 500 500 500 500 510

    510 515 525 525 525 535 549 550 570 570

    575 575 580 590 600 600 600 600 615 615

    Sample MeanSample Mean Example ContinuedExample Continued

    Monthly Rent for 70 ApartmentsMonthly Rent for 70 Apartments

  • 7/30/2019 chap4-a

    9/5799SlideSlide

    34,356490.80

    70ixx

    n 34,356 490.80

    70ixx

    n

    425 430 430 435 435 435 435 435 440 440

    440 440 440 445 445 445 445 445 450 450

    450 450 450 450 450 460 460 460 465 465

    465 470 470 472 475 475 475 480 480 480

    480 485 490 490 490 500 500 500 500 510

    510 515 525 525 525 535 549 550 570 570

    575 575 580 590 600 600 600 600 615 615

    Sample MeanSample Mean Example ContinuedExample Continued

    Monthly Rent for 70 ApartmentsMonthly Rent for 70 Apartments

  • 7/30/2019 chap4-a

    10/571010SlideSlide

    11--

    Every set of intervalEvery set of interval--level and ratiolevel and ratio--level data has alevel data has amean.mean.

    22-- All the values are included in computing the mean.All the values are included in computing the mean.33--

    A set of data has a unique mean.A set of data has a unique mean.

    44--

    The mean is affected by unusually large or small dataThe mean is affected by unusually large or small data

    values.values.55--

    The arithmetic mean is the only measure of centralThe arithmetic mean is the only measure of centraltendency where thetendency where the sum of the deviations of each valuesum of the deviations of each value

    from the mean is zero.from the mean is zero.

    Properties of the Arithmetic MeanProperties of the Arithmetic MeanProperties of the Arithmetic Mean

    ( )X X 0See next

    Slide forAn example

  • 7/30/2019 chap4-a

    11/571111SlideSlide

    Illustration of Item

    Number 5 on Previous Slide Illustration of ItemIllustration of Item

    NumberNumber

    55 on Previous Slideon Previous Slide

    Consider the set of values: 3, 8, and 4. TheConsider the set of values: 3, 8, and 4. The meanmean

    is 5.is 5.

    So (3So (3 --5) + (85) + (8 --

    5) + (45) + (4 --

    5) =5) = --2 + 32 + 3 --

    1 = 0.1 = 0.

    Symbolically we write:Symbolically we write:

    ( )X X 0

  • 7/30/2019 chap4-a

    12/571212SlideSlide

    MedianMedian

    Whenever a data set has extreme values, the medianWhenever a data set has extreme values, the medianis the preferred measure of central location.is the preferred measure of central location.

    A few extremely large incomes or property valuesA few extremely large incomes or property valuescan inflate the mean.can inflate the mean.

    The median is the measure of location most oftenThe median is the measure of location most often

    reported for annual income and property value data.reported for annual income and property value data.

    TheThe

    medianmedian

    of a data set is the value in the middleof a data set is the value in the middle

    when the data items are arranged in ascending orderwhen the data items are arranged in ascending order..

    Positioning Point n 1

    2

    Positioning Point n 1

    2

  • 7/30/2019 chap4-a

    13/571313SlideSlide

    MedianMedian

    1212 1414 1919 2626 27271818 2727

    For anFor an odd numberodd number

    of observations:of observations:

    in ascending orderin ascending order

    2626 1818 2727 1212 1414 2727 1919 7 observations7 observations

    the median is the middle value.the median is the middle value.

    Median = 19Median = 19

  • 7/30/2019 chap4-a

    14/571414SlideSlide

    1212 1414 1919 2626 27271818 2727

    MedianMedian

    For anFor an even numbereven number

    of observations:of observations:

    in ascending orderin ascending order

    2626 1818 2727 1212 1414 2727 3030 8 observations8 observations

    the median is the average of the middle two values.the median is the average of the middle two values.

    Median = (19 + 26)/2 = 22.5Median = (19 + 26)/2 = 22.5

    1919

    3030

  • 7/30/2019 chap4-a

    15/571515SlideSlide

    Median:Median: ExampleExample

    425 430 430 435 435 435 435 435 440 440

    440 440 440 445 445 445 445 445 450 450

    450 450 450 450 450 460 460 460 465 465

    465 470 470 472 475 475 475 480 480 480

    480 485 490 490 490 500 500 500 500 510

    510 515 525 525 525 535 549 550 570 570

    575 575 580 590 600 600 600 600 615 615

    Averaging the 35th and 36th data values:Averaging the 35th and 36th data values:

    Median = (475 + 475)/2 = 475Median = (475 + 475)/2 = 475

    Monthly Rent for 70 ApartmentsMonthly Rent for 70 Apartments

  • 7/30/2019 chap4-a

    16/57

    1616SlideSlide

    ModeMode

    TheThe modemode

    of a data set is the value that occurs withof a data set is the value that occurs with

    greatest frequencygreatest frequency..

    The greatest frequency can occur at two or moreThe greatest frequency can occur at two or moredifferent values.different values.

    If the data have exactly two modes, the data areIf the data have exactly two modes, the data arebimodalbimodal..

    If the data have more than two modes, the data areIf the data have more than two modes, the data aremultimodalmultimodal..

  • 7/30/2019 chap4-a

    17/57

    1717SlideSlide

    Mode:Mode: ExampleExample

    425 430 430 435 435 435 435 435 440 440

    440 440 440 445 445 445 445 445 450 450

    450 450 450 450 450 460 460 460 465 465

    465 470 470 472 475 475 475 480 480 480

    480 485 490 490 490 500 500 500 500 510

    510 515 525 525 525 535 549 550 570 570

    575 575 580 590 600 600 600 600 615 615

    450 occurred most frequently (7 times)450 occurred most frequently (7 times)

    Mode = 450Mode = 450

    Monthly Rent for 70 ApartmentsMonthly Rent for 70 Apartments

  • 7/30/2019 chap4-a

    18/57

    1818SlideSlide

    Mode: Another ExampleMode:Mode: Another ExampleAnother Example

    No ModeNo Mode

    Raw Data:Raw Data: 10.310.3

    4.94.9

    8.98.9

    11.711.7

    6.36.3

    7.77.7

    One ModeOne Mode Raw Data:Raw Data: 6.06.0

    4.94.9

    6.0 8.96.0 8.9

    6.36.3 4.94.9

    4.94.9

    More Than 1 ModeMore Than 1 Mode

    Raw Data:Raw Data: 2121 2828 2828 4141 4343 4343

  • 7/30/2019 chap4-a

    19/57

    1919SlideSlide

    Use Excel to ComputeUse Excel to Compute the Mean, Median, and Modethe Mean, Median, and Mode

    of the Following Data and Explain the Answers:of the Following Data and Explain the Answers:

    425 430 430 435 435 435 435 435 440 440

    440 440 440 445 445 445 445 445 450 450

    450 450 450 450 450 460 460 460 465 465

    465 470 470 472 475 475 475 480 480 480

    480 485 490 490 490 500 500 500 500 510

    510 515 525 525 525 535 549 550 570 570

    575 575 580 590 600 600 600 600 615 615

    STUDENTS

  • 7/30/2019 chap4-a

    20/57

    2020SlideSlide

    PercentilesPercentiles

    A percentileA percentile

    provides information about how theprovides information about how the

    data are spread over the intervaldata are spread over the interval from the smallestfrom the smallestvalue to the largest value.value to the largest value.

    Admission test scores for colleges and universitiesAdmission test scores for colleges and universitiesare frequently reported in terms of percentiles.are frequently reported in terms of percentiles.

    You are familiar withYou are familiar with percentilepercentile

    score of nationalscore of national

    educational tests such as ACT, and SAT, whicheducational tests such as ACT, and SAT, which tell youtell youwhere you stand in comparison with others.where you stand in comparison with others.

    For example, if you are in the 83th percentile, then 83%For example, if you are in the 83th percentile, then 83%

    of the testof the test--takers scored below you and you are in the toptakers scored below you and you are in the top17% of the test takers.17% of the test takers.

    P tilP til

  • 7/30/2019 chap4-a

    21/57

    2121SlideSlide

    TheTheppthth

    percentilepercentile

    of a data set is a value such that atof a data set is a value such that at

    leastleastpp

    percent of the items take on thispercent of the items take on this value or lessvalue or less

    and at leastand at least (100(100 --

    pp) percent) percent

    of the items take on thisof the items take on this

    value or morevalue or more..

    PercentilesPercentiles DefinitionDefinition

  • 7/30/2019 chap4-a

    22/57

    2222SlideSlide

    Steps for Finding PercentilesSteps for Finding Percentiles

    Arrange the data in ascending order.Arrange the data in ascending order.

    Compute indexCompute index

    ii, the, the

    positionposition

    of theof theppthth

    percentile.percentile.

    ii

    = (= (pp/100)/100)nn

    IfIf

    ii

    is notis not

    an integer,an integer, round upround up. The. Thepp thth

    percentilepercentile

    is the value in theis the value in the ii

    thth

    position.position.

    IfIf ii is an integer, theis an integer, thepp thth percentile is the averagepercentile is the averageof the values in positionsof the values in positions ii

    andand ii

    +1.+1.

  • 7/30/2019 chap4-a

    23/57

    2323SlideSlide

    8080thth

    Percentile:Percentile: ExampleExample

    ii

    = (= (pp/100)/100)nn

    = (80/100)70 = 56= (80/100)70 = 56

    Averaging the 56Averaging the 56thth

    and 57and 57thth

    data values:data values:

    80th Percentile = (535 + 549)/2 = 54280th Percentile = (535 + 549)/2 = 542

    Note: Data is in ascending order.Note: Data is in ascending order.

    425 430 430 435 435 435 435 435 440 440

    440 440 440 445 445 445 445 445 450 450

    450 450 450 450 450 460 460 460 465 465

    465 470 470 472 475 475 475 480 480 480

    480 485 490 490 490 500 500 500 500 510

    510 515 525 525 525 535 549 550 570 570

    575 575 580 590 600 600 600 600 615 615

  • 7/30/2019 chap4-a

    24/57

    2424SlideSlide

    8080thth

    Percentile:Percentile: Example ContinuedExample Continued

    At least 80%At least 80%of the itemsof the items

    take on a valuetake on a value

    of 542 or less.of 542 or less.

    At least 20%At least 20%of the itemsof the items

    take on a valuetake on a value

    of 542 or more.of 542 or more.56/70 = .8 or 80%56/70 = .8 or 80% 14/70 = .2 or 20%14/70 = .2 or 20%

    425 430 430 435 435 435 435 435 440 440440 440 440 445 445 445 445 445 450 450

    450 450 450 450 450 460 460 460 465 465

    465 470 470 472 475 475 475 480 480 480

    480 485 490 490 490 500 500 500 500 510510 515 525 525 525 535 549 550 570 570

    575 575 580 590 600 600 600 600 615 615

  • 7/30/2019 chap4-a

    25/57

    2525SlideSlide

    A B C D E

    1Apart-ment

    MonthlyRent ($) 80th Percentile

    2 1 525 =PERCENTILE(B2:B71,.8)

    3 2 440

    4 3 450 5 4 615

    6 5 480

    Use Excel to Find 80Use Excel to Find 80thth

    PercentilePercentile

    Excel Formula WorksheetExcel Formula Worksheet

    Note: Rows 7Note: Rows 7--71 are not shown.71 are not shown.

    It is not necessaryIt is not necessary

    to put the datato put the data

    in ascending order.in ascending order.

    8080thth

    percentilepercentile

  • 7/30/2019 chap4-a

    26/57

    2626SlideSlide

    8080thth

    PercentilePercentile

    Excel Value WorksheetExcel Value Worksheet

    A B C D E

    1Apart-ment

    MonthlyRent ($) 80th Percentile

    2 1 525 537.8

    3 2 440

    4 3 450 5 4 615

    6 5 480

    Note: Rows 7Note: Rows 7--71 are not shown.71 are not shown.

  • 7/30/2019 chap4-a

    27/57

    2727SlideSlide

    EXAMPLEXAMPL

    Given the following data, use Excel toGiven the following data, use Excel to

    find the 25find the 25thth percentile:percentile:

    357 550357 550654 290654 290

    763 700763 700621 789621 789

    900 605900 605

  • 7/30/2019 chap4-a

    28/57

    2828SlideSlide

    QuartilesQuartiles

    Quartiles are specific percentiles.Quartiles are specific percentiles.

    First Quartile =First Quartile = 25th Percentile25th Percentile

    Second Quartile =Second Quartile = 50th Percentile50th Percentile == MedianMedian Third Quartile =Third Quartile = 75th Percentile75th Percentile

    Unless the sample size is large, percentiles may not makeUnless the sample size is large, percentiles may not makesense, since percentiles divide the data into 100 groups.sense, since percentiles divide the data into 100 groups.

    In smaller samples, we might divide the data into fourIn smaller samples, we might divide the data into fourgroupsgroups ((quartilesquartiles).).

    Since almost any sample can beSince almost any sample can be

    divided into four groups, the quartiles are importantdivided into four groups, the quartiles are importantdescriptive statistics to explain.descriptive statistics to explain.

  • 7/30/2019 chap4-a

    29/57

    2929SlideSlide

    A B C D E

    1Apart-ment

    MonthlyRent ($) Third Quarti le

    2 1 525 =QUARTILE(B2:B71,3)

    3 2 440

    4 3 450 5 4 615

    6 5 480

    Excel Formula WorksheetExcel Formula Worksheet

    Note: Rows 7Note: Rows 7--71 are not shown.71 are not shown.

    It is not necessaryIt is not necessaryto put the datato put the data

    in ascending order.in ascending order.

    Third QuartileThird Quartile

    33rdrd

    quartilequartile

  • 7/30/2019 chap4-a

    30/57

    3030SlideSlide

    Excel Value WorksheetExcel Value Worksheet

    Third QuartileThird Quartile

    A B C D E

    1Apart-ment

    MonthlyRent ($) Third Quarti le

    2 1 525 522.5

    3 2 440

    4 3 450 5 4 615

    6 5 480

    Note: Rows 7Note: Rows 7--71 are not shown.71 are not shown.

  • 7/30/2019 chap4-a

    31/57

    3131SlideSlide

    Given the following data, use Excel toGiven the following data, use Excel to

    find the second quartile:find the second quartile:

    357 550357 550654 290654 290

    763 700763 700621 789621 789

    900 605900 605

    EXAMPLEXAMPL

  • 7/30/2019 chap4-a

    32/57

    3232SlideSlide

    Measures of VariabilityMeasures of Variability (Dispersion)(Dispersion)

    It is often desirable to consider measures ofIt is often desirable to consider measures of variabilityvariability(dispersion),(dispersion),

    as well as measures of location.as well as measures of location.

    For example, in choosing supplierFor example, in choosing supplier AA or supplieror supplier BB wewemight consider not only themight consider not only the average delivery timeaverage delivery time forforeach, but also theeach, but also the variability in delivery timevariability in delivery time for each.for each.

  • 7/30/2019 chap4-a

    33/57

    3333SlideSlide

    Measures of VariabilityMeasures of Variability (Dispersion)(Dispersion)

    RangeRange

    Interquartile Range or MidspreadInterquartile Range or Midspread

    VarianceVariance

    Standard DeviationStandard Deviation

    Coefficient of VariationCoefficient of Variation

  • 7/30/2019 chap4-a

    34/57

    3434SlideSlide

    RangeRange

    TheThe rangerange

    of a data set is the difference between theof a data set is the difference between the

    largest and smallest data values.largest and smallest data values.

    It is theIt is the simplest measuresimplest measure

    of variability.of variability.

    It isIt is very sensitivevery sensitive

    to the smallest and largest datato the smallest and largest data

    values.values.

  • 7/30/2019 chap4-a

    35/57

    3535SlideSlide

    Range:Range: ExampleExample

    425 430 430 435 435 435 435 435 440 440

    440 440 440 445 445 445 445 445 450 450

    450 450 450 450 450 460 460 460 465 465

    465 470 470 472 475 475 475 480 480 480

    480 485 490 490 490 500 500 500 500 510

    510 515 525 525 525 535 549 550 570 570

    575 575 580 590 600 600 600 600 615 615

    Range = largest valueRange = largest value --

    smallest valuesmallest value

    Range = 615Range = 615 --

    425 = 190425 = 190

    Monthly Rent for 70 ApartmentsMonthly Rent for 70 Apartments

  • 7/30/2019 chap4-a

    36/57

    3636SlideSlide

    Interquartile RangeInterquartile Range oror MidspreadMidspread TheThe interquartile rangeinterquartile range

    of a data set is the differenceof a data set is the difference

    between thebetween the third quartilethird quartile and theand thefirst quartilefirst quartile..

    It is the range for theIt is the range for the middle 50%middle 50%

    of the data.of the data.

    It overcomes the sensitivity to extreme data valuesIt overcomes the sensitivity to extreme data valuesit isit isnot effected by the extreme values.not effected by the extreme values.

    Interquartile Range Q Q3 1Interquartile Range Q Q3 1

  • 7/30/2019 chap4-a

    37/57

    3737SlideSlide

    Interquartile Range:Interquartile Range: ExampleExample

    425 430 430 435 435 435 435 435 440 440

    440 440 440 445 445 445 445 445 450 450

    450 450 450 450 450 460 460 460 465 465

    465 470 470 472 475 475 475 480 480 480

    480 485 490 490 490 500 500 500 500 510

    510 515 525 525 525 535 549 550 570 570

    575 575 580 590 600 600 600 600 615 615

    3rd Quartile (3rd Quartile (QQ3) = 5253) = 5251st Quartile (1st Quartile (QQ1) = 4451) = 445

    Interquartile Range =Interquartile Range = QQ33 --

    QQ1 = 5251 = 525 --

    445 = 80445 = 80

    Monthly Rent for 70 ApartmentsMonthly Rent for 70 Apartments

  • 7/30/2019 chap4-a

    38/57

    3838SlideSlide

    Given the following data, use Excel toGiven the following data, use Excel to

    find the Interquartile Range :find the Interquartile Range :

    357 550357 550654 290654 290

    763 700763 700621 789621 789

    900 605900 605

    EXAMPLEXAMPL

  • 7/30/2019 chap4-a

    39/57

    3939SlideSlide

    TheThe variancevariance

    is a measure of variability that utilizesis a measure of variability that utilizes

    all the data.all the data.

    VarianceVariance

    It is based on the difference between the value ofIt is based on the difference between the value ofeach observation (each observation (xxii

    ) and the mean ( for a sample,) and the mean ( for a sample,

    for a population).for a population).xx

  • 7/30/2019 chap4-a

    40/57

    4040SlideSlide

    VarianceVariance

    The variance is computed as follows:The variance is computed as follows:

    The variance is theThe variance is the average of the squaredaverage of the squareddifferencesdifferences

    between each data value and the mean.between each data value and the mean.

    for afor a

    samplesample

    for afor a

    populationpopulation

    2

    2

    ( )x

    N

    i

    22

    ( )x

    N

    i

    s

    xi

    x

    n

    22

    1

    ( )

    s

    xi

    x

    n

    22

    1

    ( )

    S d d D

  • 7/30/2019 chap4-a

    41/57

    4141SlideSlide

    Standard DeviationStandard Deviation

    TheThe standard deviationstandard deviation

    of a data set is the positiveof a data set is the positive

    square root of the variance.square root of the variance.

    It is measured in theIt is measured in the same units as the datasame units as the data,,

    makingmaking

    it more easily interpreted than the variance.it more easily interpreted than the variance.

    d dS d d D i i

  • 7/30/2019 chap4-a

    42/57

    4242SlideSlide

    The standard deviation is computed as follows:The standard deviation is computed as follows:

    for afor a

    samplesample

    for afor a

    populationpopulation

    Standard DeviationStandard Deviation

    2

    2

    2

    2

    C ffi i t f V i tiCoefficient of Variation

  • 7/30/2019 chap4-a

    43/57

    4343SlideSlide

    The coefficient of variation is computed as follows:The coefficient of variation is computed as follows:

    Coefficient of VariationCoefficient of Variation

    100 %s

    x

    100 %

    s

    x

    TheThe

    coefficient of variationcoefficient of variation

    indicates how large theindicates how large the

    standard deviation is in relation to the mean.standard deviation is in relation to the mean.

    for afor asamplesample

    for afor apopulationpopulation

    100 %

    100 %

    C ffi i t f V i tiCoefficient of Variation (C ti d)(Continued)

  • 7/30/2019 chap4-a

    44/57

    4444SlideSlide

    Measure ofMeasure of relativerelative

    dispersiondispersion

    Always a %Always a %

    CV is the standard deviation expressed as percent ofCV is the standard deviation expressed as percent ofthe meanthe mean

    Used to compare two or more groupsUsed to compare two or more groups

    Weakness: CV is undefined if the mean is zero or ifWeakness: CV is undefined if the mean is zero or ifdata are negative.data are negative.

    Thus, CV is used only for variables whose values areThus, CV is used only for variables whose values are

    X>=0X>=0

    Coefficient of VariationCoefficient of Variation (Continued)(Continued)

  • 7/30/2019 chap4-a

    45/57

    4545SlideSlide

    425 430 430 435 435 435 435 435 440 440

    440 440 440 445 445 445 445 445 450 450

    450 450 450 450 450 460 460 460 465 465

    465 470 470 472 475 475 475 480 480 480

    480 485 490 490 490 500 500 500 500 510

    510 515 525 525 525 535 549 550 570 570

    575 575 580 590 600 600 600 600 615 615

    Example ContinuedExample Continued

    Monthly Rent for 70 ApartmentsMonthly Rent for 70 Apartments

    Given the following monthly rent prices for 70 apartments, findGiven the following monthly rent prices for 70 apartments, find

    variance, standard deviation, and the coefficient of variation.:variance, standard deviation, and the coefficient of variation.: useuse

    equations & Excelequations & Excel

  • 7/30/2019 chap4-a

    46/57

    4646SlideSlide

    54.74100 % 100 % 11.15%

    490.80

    s

    x

    54.74100 % 100 % 11.15%

    490.80

    s

    x

    22 ( ) 2,996.16

    1ix xs

    n

    22 ( ) 2,996.16

    1ix xs

    n

    2

    2996.47 54.74s s 2

    2996.47 54.74s s

    the standardthe standarddeviation isdeviation is

    about 11% ofabout 11% ofof the meanof the mean

    VarianceVariance

    Standard DeviationStandard Deviation

    Coefficient of VariationCoefficient of Variation

    SolutionsSolutions

    Note thatNote that CV is the standard deviation expressed as percent ofCV is the standard deviation expressed as percent ofthe mean.the mean.

  • 7/30/2019 chap4-a

    47/57

    4848SlideSlide

    Given the following data, use Excel toGiven the following data, use Excel to

    find the followings:find the followings:

    357 550357 550654 290654 290

    763 700763 700621 789621 789

    900 605900 605

    EXAMPLEXAMPL

    EXAMPLEEXAMPLE

  • 7/30/2019 chap4-a

    48/57

    4949SlideSlide

    EXAMPLEEXAMPLE

    Given theGiven thefollowing data:following data:

    357 550357 550

    654 290654 290

    763 700763 700

    621 789621 789

    900 605900 605

    Use Excel to find:

    A.The mean

    B. The modeC.The medianD.The 75th percentile

    E.The first and the thirdquartileF.The rangeG.The interquartile range ormidspreadH. The standard deviationI.The coefficient of variation

    Use Excel to find:Use Excel to find:

    A.The mean

    B. The modeC.The medianD.The 75th percentile

    E.The first and the thirdquartileF.The rangeG.The interquartile range ormidspreadH. The standard deviationI.The coefficient of variationIf you need help with

    this, see next slides.

    If you need help withIf you need help with

    this, see next slides.this, see next slides.

    A P bl U i E lA P bl U i E l

  • 7/30/2019 chap4-a

    49/57

    5050SlideSlide

    A Problem Using ExcelA Problem Using Excel

    A private researchA private researchorganization studyingorganization studying

    families in variousfamilies in various

    countries reportedcountries reportedthe following data forthe following data for

    the amount of time 4the amount of time 4--

    year old childrenyear old childrenspent alone with theirspent alone with their

    fathers each day.fathers each day.

    Country Time with Dad(minutes)

    Belgium 30

    Canada 44

    China 54

    Finland 50

    Germany 36

    Nigeria 42Sweden 46

    U.S.A. 42

    A Problem Using ExcelA Problem Using Excel

  • 7/30/2019 chap4-a

    50/57

    5151SlideSlide

    Use Excel, answer the following questions and explainyour answers (round all numbers into two decimalplaces):

    A. The mean B. The mode

    C. The median

    D. The 75th percentile E. The first and the third quartile

    F. The range

    G. The interquartile range or midspread

    H. The standard deviation I. The coefficient of variation

    gg(Continued)(Continued)

    Note:Note: All results are rounded to two decimal places.All results are rounded to two decimal places.

    Using SWStatUsing SWStat++

  • 7/30/2019 chap4-a

    51/57

    5252SlideSlide

    gg((Creating Data AreaCreating Data Area))

    Data AreaData Area

    Using SWStatUsing SWStat++

  • 7/30/2019 chap4-a

    52/57

    5353SlideSlide

    gg(Choose Statistics; Ungrouped Data; Choose Measures)(Choose Statistics; Ungrouped Data; Choose Measures)

    Using SWStat+

  • 7/30/2019 chap4-a

    53/57

    5454SlideSlide

    g(Numerical Data, Summary Measures (Sample); Calculate)

    Using SWStatUsing SWStat++ (Results)(Results)

  • 7/30/2019 chap4-a

    54/57

    5555SlideSlide

    Using SWStatUsing SWStat+ (Results)(Results)

    Using SWStatUsing SWStat++

  • 7/30/2019 chap4-a

    55/57

    5656SlideSlide

    gg(Numerical Data; Percentile; Calculate)(Numerical Data; Percentile; Calculate)

    Using SWStatUsing SWStat++ (Results)(Results)

  • 7/30/2019 chap4-a

    56/57

    5757SlideSlide

    Using SWStatUsing SWStat (Results)(Results)

    End of Chapter 4End of Chapter 4 Part APart A

  • 7/30/2019 chap4-a

    57/57

    End of Chapter 4,End of Chapter 4, Part APart A