Using StatCrunch

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:

d. χ2 = 9.88, df = 2, α = 0.01        

c. χ2 = 10.67, df = 3, α = 0.01      

b. χ2 = 8.09, df = 4, α = 0.05       

a. χ2 = 3.02, df = 1, α = 0.05       

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

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.