Consider the following statements and indicate whether they are true or false and briefly explain your answer to each one. (5 points each).

1. Randomized clinical trials are not vulnerable to selection bias.

1. Missing data can lead to selection bias in any study regardless of design.

Non-differential loss to follow-up can bias the estimated measure of association.

1. Non-differential loss to follow-up will reduce sample size and result in decrease precision of the results (a wider confidence interval).

1. In a case-control study it is important to sample controls independently of exposure in order to obtain controls who are representative of the population from which the cases arose.