Week 3 Assignment

1. (3 pts) Using StatCrunch, construct a labeled contingency table (with row, column, and total %s), as well as the contribution to the chi-square statistic, for the following set of data for 300 people:

Group A Group B Group C Total

Had flu shot 20 30 38 88

Didn't have flu shot 80 70 62 212

Total 100 100 100 300

Is the value of the chi-square statistically significant?

2. (1 pt) Write short paragraph summarizing the results of the analysis in Exercise 1.

3. (3 pts) Using StatCrunch, construct a labeled contingency table (with row, column, and total %s), as well as the contribution to the chi-square statistic, for the following set of data for 180 people undergoing a knee replacement treatment with a drug supplement:

Treatment with drug XTreatment without Drug X Total

Had > 8 wk rehab 18 30 48

Had < 8 wk rehab 70 62 132

Total 88 92 180

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

4. (1 pt) Write short paragraph summarizing the results of the analysis in Exercise 3.

5. (1 pt) Given each of the following circumstances, determine whether the calculated values of chi-square are statistically significant:

1. ² = 3.02, df = 1, = 0.05
2. ² = 8.09, df = 2, = 0.05
3. ² = 12.67, df = 3, = 0.01
4. ² = 9.01, df = 2, = 0.01

6. (1 pt) 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

7. (1 pt) Using the information provided, indicate which statistical test you think should be used for each of the following situations (a-d):

1. Independent variable: normal birth weight vs. low birth weight infants; dependent variable: breathing rate (in breaths per minute).
2. Independent variable: time of measurement of same patient (before and after surgery); dependent variable: heart rate.
3. Independent variable: time of measurement (before, during, and after intervention); dependent variable: did vs did not exercise regularly.
4. Independent variable: infertility treatment A vs infertility treatment B vs control condition; dependent variable: did vs did not become pregnant.

8.(3 pts) The relationship between cigarette smoking and major depressive disorder has been studied for decades. In the assignment area, 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 labeled contingency table for this data as you did for Exercise 1 and 3 above.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?

9. (1 pt) Write brief paragraph summarizing the results of the analysis in Exercise 8.What can you conclude about smoking and depression ("Feeling Down") in this sample?

10. (4 pts) Using the data set from this week's discussion thread, question 2 from the Pew Research Study on Aging (Nashville), load the data set into StatCrunch and calculate the chi-square statistic and degrees of freedom for the items "Marital" and a measure of dementia, "Forgot date".Construct a labeled contingency table for this data as you did for Exercise 8 above.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?What hypotheses did you test and what can you conclude about marriage status and dementia in this sample?

11.(1 pt) Below are two (a and b) 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. b.

Aspirin Taker?

Cancer

No

Yes

Yes

% within Cancer

% within Aspirin Taker

Expected Counts

28

(58.33%)

(29.17%)

24.91

20

(41.67%)

(22.47%)

23.09

No

% within Cancer

% within Aspirin Taker

Expected Counts

68

(49.64%)

(70.83%)

71.09

69

(50.36%)

(77.53%)

65.91

Smoker

Diabetes

No

Yes

Yes

% withinDiabetes

% within Smoker

Expected Counts

2

(25%)

(4.878%)

4

6

(75%)

(14.63%)

4

No

% withinDiabetes

% within Smoker

Expected Counts

39

(52.7%)

(95.12%)

37

35

(47.3%)

(85.37%)

37