Which of the Following Statements Is True About Case-Control Designs

Multiple Choice

Which of the following statements is true about case-control designs?

A) They rarely are feasible.
B) Data must be collected at multiple points in time.
C) Retrospective data are collected about past differences that might explain differences in outcome.
D) We usually can be highly confident about their internal and external validity.
E) We usually can be highly confident about the direction of causal influence.