Don’t catch a cold! A recent study of 1000 students at the University of Michigan investigated how to prevent catching the common cold. The students were randomly assigned to three different cold prevention methods for 6 weeks. Some wore masks, some wore masks and used hand sanitizer, and others took no precautions. The two groups who used masks reported 10–50% fewer cold symptoms than those who did not wear a mask.62

(a) Does this study allow for inference about a population?

Explain.

(b) Does this study allow for inference about cause and effect? Explain.