How Do I Distinguish Between Valid Research and Bad Research?

I had a radio station try to tell me that his radio station (a hard rock station) reached customers of this upscale department store in Washington, D.C. That didn’t make sense to me. I had shopped in that particular department store and I knew who else shopped there – mainly blue-haired old ladies – not your typical rockers. I asked to see this “research.” My rep e-mailed it over to me, and the first thing I noticed was that the respondent group (number of people who were included in the study) was under 200. My rule of thumb was that if the study wasn’t bigger than a 200 base, I tossed it out, which is exactly what I did. Did I buy that station? Of course not.