Why some comments are good and others suck

The comments on The Hannibal Blog tend to be excellent–witty, funny, sophisticated–which is a great thrill to me because it suggests that my blog draws interesting (and I dare say erudite) readers.

By contrast, the comments on the website of my employer, The Economist, tend overwhelmingly to be banal, moronic and useless. There are gems in there, but on they whole the comments are so bad that, internally, we recently spent a long, long time discussing what to do about that.

So I was delighted when I came across a very well-thought-out post on the blog of Nicolas Kayser-Bril, a media economist. Given the publication I write for, it should have occurred to me to apply the logic of economics to the problem. Oh well, Nicolas beat me to it.

The problem is captured, as Nicolas shows, in this chart:

As Nicolas explains,

the more commenters you have, the more likely it is that one of them is a troll. … That’s why I drew the blue curve of the marginal value of a single comment. It decreases as an inverse function of the number of commenters, itself a function of the size of the audience.

Hence the red line: as the audience grows in size, the total value of comments increases more slowly.

Now for moderation. I’m assuming that the cost of moderating a single comment remains constant, so that the total cost of moderation increases linearly. Just look at the curve. At some point, it costs more to moderate comments that to get rid of them…

My point is simply that a larger audience automatically leads to a conversation of lesser value, relative to the number of participants.

The answer to the vexing issue of why The Hannibal Blog has great comments while The Economist has awful comments thus appears shockingly simple: The former has a small audience, the latter a large audience.

I will let this percolate through my morning brain. There may be concrete, real-world implications in this….