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
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