1. Assume we are carrying out a study involving children between the ages of 6 months and 2 ½ years. We are looking at the effort of sudden noise on behavioral response. The most important variable to match the groups on is?

a) birth order

b) eye color

c) age

d) weight

2. The analysis of covariance (ANCOVA) is generally useful for _______________

a) removal of interaction effects

b) statistical removal of variability caused by extraneous variables

c) analyzing more than one independent variable

d) all of the above