Confounding variables are nothing new, so controlling form them are common. However, as this paper shows, a lot of these controls are flawed, calling into question the validity of the results. SEM is proposed as part of the solution.
Does ice cream cause drownings? Let’s think about this statistically. Consider that, in any given city, daily sales of ice cream are, most likely, positively correlated with daily rates of drownings. Now, no matter how strong this correlation is, it doesn’t really mean that ice cream is dangerous.