To find out what proportion of Americans support proposed Medicare legislation to help pay medical costs, the AARP conducted a survey of their members (people over age 50 who pay membership dues). One of the questions was: “Even if this plan won’t affect you personally either way, do you think it should be passed so that people with low incomes or people with high drug costs can be helped?” Of the respondents, 75% answered “Yes.”4

a. Describe how undercoverage might lead to bias in this study. Explain the likely direction of the bias.

b. Describe how the wording of the question might lead to bias in this study. Explain the likely direction of the bias.