Chapter 22, Problem 37E

Cranberry juice It’s common folk wisdom that drinking cranberry juice can help prevent urinary tract infections in women. In 2001, the British Medical Journal reported the results of a Finnish study in which three groups of 50 women were monitored for these infections over 6 months. One group drank cranberry juice daily, another group drank a lactobacillus drink, and the third drank neither of those beverages, serving as a control group. In the control group, 18 women developed at least one infection, compared to 20 of those who consumed the lactobacillus drink and only 8 of those who drank cranberry juice. Does this study provide supporting evidence for the value of cranberry juice in warding off urinary tract infections?

1. a) Is this a survey, a retrospective study, a prospective study, or an experiment? Explain.
2. b) Will you test goodness-of-fit, homogeneity, or independence?
3. c) State the hypotheses.
4. d) Check the conditions.
5. e) How many degrees of freedom are there?
6. f) Find χ² and the P-value.
7. g) State your conclusion.
8. h) If you concluded that the groups are not the same, analyze the differences using the standardized residuals of your calculations.