Violent acts on prime-time TV. A typical hour of prime-time television shows three to five violent acts. Linking family interviews and police records shows a clear association between time spent watching TV as a child and later aggressive behavior
(a) Explain why this is an observational study rather than an experiment.
(b) Suggest several variables describing a child's home life that may be related to how much TV he or she watches. How would the effects of these variables make it difficult to conclude that more TV causes more aggressive behavior?