Regression To The Mean – How to Sell BullShit

A few years ago I was getting a cold, or at least I had some of the symptoms that I thought were indicative of getting a cold. And it was a reasonable conclusion because I hadn’t been sleeping very well and was working a lot. I mentioned that I though I was getting sick to a peer and he asked “do you have a cold now or do you think you might be getting one?”

I replied with “I think I might be getting one.”

“Okay, take this” and he handed me a small bottle of pills, 15 of them with the instructions take 2 now and 2 every 2 hours until they are gone. I wondered why there was an odd number of pills but did as he instructed. And they worked. I never got a cold. This was amazing, I didn’t get sick and it only cost me $16 – I got the friend price, other people were buying the cold prevent for $26.

The next day I asked him what he would have recommended had a cold already taken hold and he showed me a different pill bottle. It was the same size and had the same instructions but a different name. This was a cold cure.

You can imagine just how grateful I was, a month later, when I started to feel sick again, that he was willing to sell me more. This time the cold took hold in-spite of me consuming another bottle of the cold prevent. So I bought a bottle of the cold cure, it was more expensive but I got the friend price. I remained sick. The $16 prevent and the $20 cure didn’t do anything.

So what had happened, why did it work the first time and nothing worked the second time?

The explanation is very interesting and it reveals as much about human psychology and as it does about the tricks charlatans use to take your money.

Three things were at play. First off, I trusted my friend. We had been friends for more than 10 years and I believed that he knew things. Even though I know better, I valued his opinion and believed that he wouldn’t take advantage of our friendship to help sell supplements. Next, I saw a pattern between taking the cold prevent pills and getting better. Human beings evolved to notice patterns and well find them even when they do not exist. Considering that I did other things on the same day that I took the first bottle of cold prevent pills that may have impacted my internal environment – ate more vegetables, ate more fruit, went to bed earlier, watched some funny cat videos on YouTube, etc…. – I made a conscious decision to link the pills with the outcome. Finally, maybe I wasn’t getting a cold in the first place. Maybe I was having an allergic reaction to something in the air, maybe I ate some food that caused cold like symptoms. Or maybe my body was able to fight off the cold on its own and I wasn’t ever going to get sick.

It’s the final thing that is most important here. The human body is an amazing thing and it is fantastic at fighting off infections, illness and the things that cause disease. We’ve evolved to be self healers and our immune system just does its job, without us asking it to do so and without much outside influence. In most cases and with most people, the body fights off illness / sickness and disease and returns to normal. The further away your state happens to be from your normal state, the more likely it is to return to its normal state in the near and immediate future.

This tendency for things to return to normal is called regression to the mean, when paired with our tendency to see patterns that don’t exist, contributes to the formation of erroneous connection between two unrelated things. The cure my friend sold me was worthless. I was going to feel better the following day anyway. I could have taken sugar pills or nothing at all and the impact would have been the same. I know this because the cure didn’t work the second time and in the months that followed, many of the other people who were sold the cold prevent got sick.

Just because two things happen around the same time does not mean that they are connected in any way whatsoever. The people were going to get better anyway, that is the nature of a regression towards the mean. And it is why anecdotal reports are not considered evidence.