Hospital floors are usually bare tiles instead of carpet. Carpets will decrease noise but might increase germ growth. To study this, researchers installed carpet in 8 of 16 hospital rooms. They randomly selected the rooms to carpet. The other rooms had bare tiles.
After two weeks of normal use, they collected air samples from the rooms and counted the bacteria in each sample. To identify the explanatory and response variables, match each of the following with one of the terms on the right. Note - any given term may be used more than once or not at all.
a. A control group
b. Direct control of confounding variables
c. Random assignment