A group of scientists is conducting an experiment on the effects of media on children. They random
child to one of four treatment groups. Each treatment group has a specific amount of screen time d
no screen time, the second group has two hours of screen time, the third group has four hours of s
screen time.
After the first week, the scientists conduct the same experiment, with the same subject groups, for
each of the four treatments.
Which statements about this study are true?