I know. I was too.

Some of them ask for you to pay for the results. Others are studded with advertisements. Some just want higher traffic. The basic point is that all want more users.

With that in mind, let’s consider which types of tests are most “successful” (in the sense I previously described). Suppose I took N tests (Call them T1, T2, …, TN) and I scored best in Ti. If my goal of taking the test is to share my results, my natural instinct is to share the results from Ti–by screen-shooting it, for instance. Therefore, Ti will get more exposure among my friends.

But I’m not the only one who prefers to share the highest score rather than the lowest; that goes for everyone. As an economist, I believe that incentives play a crucial role in human behavior: In this case we see how the incentives have been skewed for the online IQ test websites. Each test has the incentive to be more generous with its reported score.

I was recently prodded to take another test. The result? 160. Is that reasonable? No. The questions were too simple to accurately distinguish people by intelligence up to the 4th standard deviation above the mean (Yes, that’s the top 0.003% of humankind, completely unreasonable for an online test). Did the website really believe that only 0.003% of its visitors ever got all questions right? (If that really was the case, the website must have exceptionally slow visitors) But just to show what I mean by skewed incentives, I’ll upload the print-to-PDF file from just before I submitted my answers.

My point? Online IQ tests cannot be trusted, and your real IQ may be significantly lower than what you’re told.