Think you can trust your instincts when it comes to marketing? Check out these ten common mistakes in marketing to make sure your campaign is logically sound.

1. Mistaking an argument for proof Despite elegant arguments that stress causes ulcers, the culprit turned out to be a bacterium. The argument that creativity is the key to advertising success is no less elegant, and no closer to the mark.
2. Post hoc, ergo propter hoc (“After this, therefore because of this”) It’s tempting to assume that what happened first caused what happened next. But before you conveniently decide that the new ad campaign made sales go up or down, consider what else was going on. Sometimes weather has an effect.
3. Anecdotes as conclusive Many police officers “know” from personal experience that crime increases under a full moon, but actual records show it isn’t so. Beware basing marketing decisions on anecdotes, even from reliable sources. Stories aren’t evidence.
4. Stereotyping No, more men won’t buy your industrial product if you put a sexy woman in your ad. Before assuming how a given population will act, test and watch.
5. God of the gaps Ancient humans filled in their knowledge gaps by chalking up the unexplainable to everything from the stars to the gods. Marketers do that when they automatically credit high sales to their pet god of the gaps (advertising, location, dress code, accounting, you name it) and blame low sales on their pet scapegoat (advertising, location, dress code, accounting, you name it).
6. All or nothing Vaccinations don’t work on everyone, but they work on the vast majority, so we’d be foolish to halt them. It would be equally foolish to stop a successful ad campaign because of a few complaints or to continue an unsuccessful one because of a few compliments.
7. Self-serving research There’s only one correct answer to, “Do you like my new haircut?” The point of research should be to discover, not to get people to say what you want to hear.
8. Sneaky biases Remember those police officers who correlate crime with lunar phases? They are inadvertent victims of hindsight and selection bias recalling cases that confirm and overlooking those that don’t. Biases sneak up on the best of us. When you’re tempted to recall what all successful marketing campaigns have in common, resist. Consult the data instead.
9. Inventing objectives after the fact Sometimes ad campaigns are deemed “successful” for a result that wasn’t in the plan. “Sales fell, but the campaign won three awards” works only if the original goal was to win awards regardless of sales.
10. Confusing correlation and causation Ask any economist: Correlations are often mere coincidence. I knew an advertiser who was convinced that ads with her photo in them outsold ads without. The correlation was valid, but the photos weren’t the cause. The other ads had weaker headlines and ran in off-target publications. Dig deep before deciding what causes what.