Nothing Special   »   [go: up one dir, main page]
Scribd Logo
Upload

Welcome to Scribd!

  • 13 views

    M2 Practice Problem SolutionB

    Uploaded by

    tsion beza

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd

    M2 Practice Problem SolutionB

    Uploaded by

    tsion beza
    13 views4 pages

    Original Title

    M2_Practice_Problem_SolutionB

    Copyright

    © © All Rights Reserved

    Available Formats

    DOCX, PDF, TXT or read online from Scribd

    Did you find this document useful?

    Is this content inappropriate?

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    13 views4 pages

    M2 Practice Problem SolutionB

    Uploaded by

    tsion beza

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    of 4

    MPH501 Module 2 Assignment B Solutions

    Quantitative Methods for Pub Health Application

    Chapter 4 Solutions to Problems

    1. A study is run to estimate the mean total cholesterol level in children 2-6 years of age. A
    sample of 9 participants is selected and their total cholesterol levels are measured as
    follows.

    185 225 240 196 175 180 194 147 223

    X X2
    147 21,609
    175 30,625
    180 32,400
    185 34,225
    194 37,636
    196 38,416
    223 49,729
    225 50.625
    240 57,600
    1765 352,865

    a. Compute the sample mean.

    ΣX 1,765
    X̄ = = =196 . 1
    n 9

    b. Compute the sample standard deviation.

    s=
    √
    ΣX 2−( ΣX )2 /n
    n−1
    =
    √
    352,865−(1,765 )2 /9
    9−1
    =
    8 √
    352,865−(3,115,225/9 )

    =
    √ 8
    =
    8√
    352,865−346,136 . 1 6,728 . 89
    = √ 841 . 1=29 .0

    c. Compute the median.

    Median=194

    d. Compute the first and third quartiles.

    Q1 = 177.5 ((175+180)/2) Q3=224 ((223+225)/2)

    © 2012 Jones & Bartlett Learning, LLC 1


    MPH501 Module 2 Assignment B Solutions
    Quantitative Methods for Pub Health Application
    e. Which measure, the mean or median, is a better measure of a typical value? Justify.

    Check for outliers: IQR = 224-177.5 = 46.5

    Lower Limit = 177.5 – 1.5(46.5) = 107.8


    Upper Limit = 224 + 1.5(46.5) = 293.8

    No outliers, therefore the best measure of a typical value is the sample mean 196.1.

    f. Which measure, the standard deviation or the interquartile range, is a better measure of
    dispersion? Justify.

    Because there are no outliers, the best measure of dispersion is the sample
    standard deviation, s=29.0.

    4. The following data were collected as part of a study of coffee consumption among graduate
    students. The following reflect cups per day consumed:

    3 4 6 8 2 1 0 2

    X X2
    0 0
    1 1
    2 4
    2 4
    3 9
    4 16
    6 36
    8 64
    26 134

    a. Compute the sample mean.

    ΣX 26
    X̄ = = =3. 3
    n 8

    © 2012 Jones & Bartlett Learning, LLC 2


    MPH501 Module 2 Assignment B Solutions
    Quantitative Methods for Pub Health Application
    b. Compute the sample standard deviation.

    s=
    √
    ΣX 2−( ΣX )2 /n
    n−1
    =
    √
    134−( 26 )2 /8
    8−1
    =
    7 √
    134−84 . 5
    =√ 7 .36=2 .7

    c. Compute the median.

    Median = 2.5 ((2+3)/2 = 2.5)

    d. Compute the first and third quartiles.

    Q1 = 1.5 ((1+2)/2=1.5) Q3=5.0 ((4+6)/2=5.0)

    e. Which measure, the mean or median, is a better measure of a typical value? Justify.

    Q1 = 1.5 Q3=5.0

    Check for outliers: IQR = 5.0-1.5 = 3.5

    Lower Limit = 1.5 – 1.5(3.5) = -3.75


    Upper Limit = 5.0 + 1.5(3.5) = 10.25

    No outliers.

    No outliers, therefore the best measure of a typical value is the sample mean 3.3.

    f. Which measure, the standard deviation or the interquartile range, is a better measure of
    dispersion? Justify.

    Because there are no outliers, the best measure of dispersion is the sample standard deviation,
    s=2.7.

    5. In the study of a new anti-hypertensive medication, systolic blood pressures are measured at
    baseline (or the start of the study before any treatment is administered). The data are as
    follows:

    120 112 138 145 135 150 145 163


    148 128 143 156 160 142 150

    © 2012 Jones & Bartlett Learning, LLC 3


    MPH501 Module 2 Assignment B Solutions
    Quantitative Methods for Pub Health Application
    a. Compute the sample mean.

    X̄ =142.3 .

    b. Compute the sample median.

    Median = 145.

    c. Compute the sample standard deviation.

    s = 14.1.

    d. Compute the sample range.

    Range = 163-112 = 51.

    e. Are there any outliers? Justify.

    Q1 = 135 Q3=150

    Check for outliers: IQR = 150 – 135 = 15

    Lower Limit = 135 – 1.5(15) = 112.5


    Upper Limit = 150 + 1.5(15) = 172.5

    The value of 112 is an outlier on the low end (less that the lower limit of 112.5).

    Median = 8 and IQR = 5

    © 2012 Jones & Bartlett Learning, LLC 4

    You might also like