It is possible that watching public television makes people want to have more sex. It is equally possible, however, that some third variable, such as health or education, influences both television...

It is possible that watching public television makes people want to have more sex. It is equally possible, however, that some third variable, such as health or education, influences both television preferences and sexual behavior. It is even possible that having sex makes people want to watch more public television. Based on the correlation the researchers reported, there is no way of telling which of these explanations is true.