how to tell statistics from damned lies
Betsey Stephenson and Justin Wolfers (two prominent economists at the University of Michigan) wrote a list of six things that can help the non-expert decide whether empirical research is useful or not. This one I particularly liked:
3. Be wary of scholars using high-powered statistical techniques as a bludgeon to silence critics who are not specialists. If the author can’t explain what they’re doing in terms you can understand, then you shouldn’t be convinced. You wouldn’t be convinced by an analysis just because it was written in ancient Latin, so why be impressed by an abundance of Greek letters? Sophisticated statistical methods can be helpful, but they can also hide more than they reveal.