Below are three sets of expected frequencies for the four cells of 2 X 2 contingency tables. ...

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

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.

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

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.

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

b. χ2 = 8.09, df = 4, α = 0.05

c. χ2 = 10.67, df = 3, α = 0.01

d. χ2 = 9.88, df = 2, α = 0.01

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

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: 1 minute Apgar scores (1-10 scale).

b. Independent variable: time of measurement (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.

8. Below are three sets of expected frequencies for the four cells of 2 X 2 contingency tables. Identify which statistical procedure would be appropriate for each, using the most conservative approach.

a. 4 4 b. 35 35 c. 9 9

21 21 65 65    91 91