Paul Krugman wrote a post about the ECB yesterday. I agree with it about, I don't know, say 90%. Here's where I disagree:
1. Paul and I both want easier monetary policy for the ECB, but he thinks of that as a temporarily higher target inflation rate, and I think it would be better to have a temporarily higher NGDP growth rate leading to a level path for NGDP.
2. I think it would have been useful if Paul had distinguished between what is necessary to save the Euro and whether it is worth saving.
3. Ummmm. I think a reference to a "Darwin Award" for the ECB, like in my old post, would have made a sexier title than "ECB Death Wish". Plus, he could have linked to my old post, which would have given me more fame and readers.
This post doesn't really have any point, does it? It's really not worth writing.
But that is exactly my point, and why I wrote it.
If Paul Krugman had written something I totally disagreed with I would have been much more likely to have written a post saying why I thought he was wrong. I have done that several times in the past. And it would have been a much more interesting post.
Even in this post, which I would not normally have written, I have talked only about the bits where I disagree with Paul Krugman. I said nothing about the bits where I agree (except where I needed to in order to explain more clearly where I disagree).
There is a big selection bias in what we blog about. People reading blog posts who are unaware of this selection bias will get a very distorted view that considerably exaggerates how much disagreement there is between economists.
Plus, I am much more likely to write a post if I disagree with someone like Paul Krugman who has lots of readers than to write a post if I disagree with some other blogger who has fewer readers. This means that the average reader of blogs will observe more disagreement between bloggers than the average blogger observes. (I think I said that right). This amplifies the bias towards reading about disagreement.
All of this is also true for comments on blogs.
I think this selection bias is bigger for blogs than for other media, like journal articles, though I think it's still present there. I don't have any solutions to this problem. I don't think it really is a problem, just as long as people are aware of it.
The only real point of this post is to try and make a few more people aware of the selection bias, just in case they hadn't already figured it out for themselves, and to provide an example to illustrate the point.
(Philosophical question for econometricians: if an estimator is biased, but you know it is biased, even if you don't know how big that bias is, is your personal subjective estimate still biased?)