Week 3 Assignment | Complete Solution

Week 3 Assignment

1.    Using StatCrunch, calculate the chi-square statistic and degrees of freedom for the following set of data for 300 people:

                    Group A    Group B    Group C    Total
        Had flu shot             20            30            32           82
        Didn’t have flu shot         80            70            68           218
        Total                 100           100           100          300

Use Tables =>  Contingency => with summary-will cover in the Collaborate session

    Is the value of the chi-square statistically significant at the 0.05 level?  

2.    Write a paragraph summarizing the results of the analysis in Exercise 1.

Key things to include in a write:

•    What the study is about (i.e. what is the research question?)
•    Where the results are significant or not
•    A conclusion sentence to indicate the answer to the research question (i.e., is there an effective of the IV or not?

3.    Using StatCrunch, calculate the chi-square statistic and degrees of freedom for the following set of data for 180 people undergoing a knee replacement treatment with a drug supplement:

                Treatment with drug X    Treatment without Drug X       Total
    Had > 8 wk rehab             18                32              50       
Had < 8 wk rehab             70                60                  130
            Total        88               92               180

Use Tables =>  Contingency => with summary -will cover in the Collaborate session

    Is the value of the chi-square statistically significant at the 0.05 level?  

4.    Write a paragraph summarizing the results of the analysis in Exercise 3.

See #2

5.    Given each of the following circumstances, determine whether the calculated values of chi-square are statistically significant:

a.    χ2 = 3.02, df = 1, α = 0.05 indicate if sig or not sig
b.    χ2 = 8.09, df = 2, α = 0.05
c.    χ2 = 10.67, df = 3, α = 0.01
d.    χ2 = 9.88, df = 2, α = 0.01
Use chi-square table on page 416

6.    Match each of the nonparametric tests in Column A with its parametric counterpart in Column B

    A. Nonparametric Test        B.  Parametric Test
        1.  Mann-Whitney U-test        a.  Paired t-test
        2.  Friedman test            b.  One-way ANOVA
        3.  Kruskall-Wallis test        c.  Independent groups t-test
        4.  Wilcoxon signed-ranks test    d.  Repeated measures ANOVA
Use Blue slides #19

7.    Using the information provided, indicate which statistical test you think should be used for each of the following situations:

a.    Independent variable: normal birth weight vs. low birth weight infants; dependent variable: breathing rate (in breaths per minute).
b.    Independent variable: time of measurement of same patient (before, during, and after surgery); dependent variable: heart rate.
c.    Independent variable: time of measurement (before, during, and after intervention); dependent variable: did vs did not exercise regularly.
d.    Independent variable: infertility treatment A vs infertility treatment B vs control condition; dependent variable: did vs did not become pregnant.
Use Blue slides #19

8.         The relationship between cigarette smoking and major depressive disorder has been studied for decades. In the doc sharing area of the course, you will find an excel spreadsheet of data from a study on smoking and depression by the St Louis Epidemiologic Catchment Area Survey of the National Institute of Mental Health.  The file is labeled “Catchment Area Survey”.  Using this data set in StatCrunch, calculate the chi-square statistic and degrees of freedom for the items “smoker” and a measure of depression, “FeltDown”.  Construct a contingency table for this data as we did in week 1.  Be sure to include and label the row, column and total %’s as well as the expected counts.  Is the value of the chi-square statistically significant at the 0.05 level?  Any reason to use a correction to the chi-square test here given your expected counts?  

This data file can be found under “Week Three”

Use Tables =>  Contingency => with Data
9.    Write a paragraph summarizing the results of the analysis in Exercise 8.  What can you conclude about smoking and depression (“Feeling Down”) in this sample?

10.       Below are three (a-c) sets of cells of 2 X 2 contingency tables including the expected frequencies (Totals not included).  Identify which statistical procedure would be appropriate for each, using the most conservative approach.

a.    
    Aspirin Taker?
Cancer    No    Yes
Yes
% within Cancer
% within Aspirin Taker
 % of Total
Expected Counts    28
(58.33%)
(29.17%)
(15.14%)
24.91    20
(41.67%)
(22.47%)
(10.81%)
23.09
No
% within Cancer
% within Aspirin Taker
 % of Total
Expected Counts    68
(49.64%)
(70.83%)
(36.76%)
71.09    69
(50.36%)
(77.53%)
(37.3%)
65.91

b.
    Room Type
Infection    Concrete    Linoleum
Yes
% within Infection
% within Room Type
% of Total
Expected Counts    2
(9.091%)
(5.882%)
(1.626%)
6.08    20
(90.91%)
(22.47%)
(16.26%)
                   15.9
No
% within Infection
% within Room Type
% of Total
Expected Counts    32
(31.68%)
(94.12%)
(26.02%)
27.9    69
(68.32%)
(77.53%)
(56.1%)
73.1

c.
    Smoker
Diabetes    No    Yes
Yes
% within  Diabetes
% within Smoker
% of Total
Expected Counts    2
(25%)
(4.878%)
(2.439%)
4    6
(75%)
(14.63%)
(7.317%)
4
No
% within  Diabetes
% within Smoker
% of Total
Expected Counts    39
(52.7%)
(95.12%)
(47.56%)
37    35
(47.3%)
(85.37%)
(42.68%)

37 Potential Answer for Each - Fisher’s, Yates, or Chi-square