December 15, 2017

Public comments, petitions, and other self-selected samples

In the US, the Federal Communications Commission was collecting public comments about ‘net neutrality’ — an issue that’s commercially and politically sensitive in a country where many people don’t have any real choice about their internet provider.

There were lots of comments: from experts, from concerned citizens, from people who’d watched a John Oliver show. And from bots faking real names and addresses on to automated comments.   The Wall Street Journal contacted a random sample of nearly 3000 commenters and found the majority of those they could get in contact with had not submitted the comment attached to their details.  The StartupPolicyLab attempted to contact 450,000 submitters, and got a response from just over 8000. Of the 7000 contacted about pro-neutrality comments, nearly all agreed they had made the comment, but of the 1000 responses about anti-neutrality comments, about 88% said they had not made the comment.

It’s obviously a bad idea to treat the comments as a vote. Even if the comments were from real US people, with one comment each, you’d need to do some sort of modelling of the vast majority who didn’t comment.  But what are they good for?

One real benefit is for people to provide ideas you hadn’t thought of.  The public comment process on proposed New Zealand legislation certainly allows for people like Graeme Edgeler to point out bugs in the drafting, and for people whose viewpoints were not considered to speak out.  For this, it doesn’t matter what the numbers of comments are, for and against. In fact, it helps if people who don’t have something to say don’t say it.

With both petitions and public comments there’s also some quantitative value in showing that concern about some issue you weren’t worrying about isn’t negligibly small; that thousands (in NZ) or hundreds of thousands (in the US) care about it.

But if it’s already established that an issue is important and controversial, and you care about the actual balance of public opinion, you should be doing a proper opinion poll.


Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »