Ever wondered why some comments appear more than others and why some comments only appear on blogs with many readers? The explanation is fairly simple: human psychology and statistics.

Great timing. I was just doing this …
It is self-evident that for a post with some relevance to real life activities, the probability of a person engaged or about to be engaged in such an activity multiplied by the probability of the person commenting (these probabilities are not necessarily independent, but I doubt the cancel each other out, if anything they increase as someone with some reason to comment are more likely to comment) multiplied with the number of people reading the post exceeds 1. Hence, the more readers a blog has, the more “great timing” comments there will be. Trent over at TSD probably has some of the most “great timing” comments in the world because he frequently write about every day activities and he has a lot of commenters.

In fact, it is very interesting just how much can be explained by random fluctuations. Particularly rare events. As a ground rule, if events have no “memory” but you otherwise have no idea about their distribution, a good rule is that your uncertainty is 1/SQRT(N), where N is the number of observations. If N=3, I would not make any conclusions whatsoever. But then again, I like to play it safe 😉

Great post, I agree.
This is simply confirmation bias. It has been amply demonstrated that humans mainly look for positive tests, that is, proving their hypothesis, rather than negative tests, that is, disproving their hypothesis. The scientific ideal would be the latter because there are many ways a theory can be wrong but only on way it can be right, so if you’re seeking truth, that is the way to go. On the other hand if using a positive test, there are many ways to affirm the test and in this case the test will stop with the first positive affirmation. This also means that humans will seek out people who agree with them and read artiles that confirm their beliefs or their biases, rather than articles that challenge them. If people believe that their own beliefs are “great”, then we have the “great post, I agree” comment.

I disagree, this post sucked.
This comment is likely not made by a regular reader but rather by a visiting reader who stumbled onto the post by accident. However, the psychological reasons are the same as above. It failed to confirm the bias and since the bias is great, the post must suck.

Originally posted 2010-03-08 00:46:44.