Three-fourths of all conceptions fail to survive beyond 6 weeks

Therapy outcome studies typically have a no-treatment control group, but results from such studies can be difficult to interpret because

a. people waiting for therapy often seek counseling and advice from others. b. it is not possible to randomly assign people to that group. c. the control group patients usually improve more than the treated patients. d. nobody wants to wait for therapy.

What is the most popular form of physical activity in America?

a) walking b) jogging c) running d) cycling