Studies have shown that people who marry and divorce have, on average, fewer children than do people who stay married, suggesting that having more children makes divorce less likely.

a. Explain why there might be sampling bias in this study.

b. Suppose that the chances of getting divorced are not affected by the number of children you have. Explain how it could still be the case that people who marry and divorce have, on average, fewer children than do people who stay married.

c. What would have to be done to have a controlled experiment?