Tag: nate silver

Opinion polling in India and the US

(Relative) old-time readers of this blog might recall that in 2013-14 I wrote a column called “Election Metrics” for Mint, where I used data to analyse elections and everything else related to that. This being the election where Narendra Modi suddenly emerged as a spectacular winner, the hype was high. And I think a lot of people did read my writing during that time.

In any case, somewhere during that time, my editor called me “Nate Silver of India”.

I followed that up with an article on why “there can be no Nate Silver in India” (now they seem to have put it behind a sort of limited paywall). In that, I wrote about the polling systems in India and in the US, and about how India is so behind the US when it comes to opinion polling.

Basically, India has fewer opinion polls. Many more political parties. A far more diverse electorate. Less disclosure when it comes to opinion polls. A parliamentary system. And so on and so forth.

Now, seven years later, as we are close to a US presidential election, I’m not sure the American opinion polls are as great as I made them out to be. Sure, all the above still apply. And when these poll results are put in the hands of a skilled analyst like Nate Silver, it is possible to make high quality forecasts based on that.

However, the reporting of these polls in the mainstream media, based on my limited sampling, is possibly not of much higher quality than what we see in India.

Basically I don’t understand why analysts abroad make such a big deal of “vote share” when what really matters is the “seat share”.

Like in 2016, Hillary Clinton won more votes than Donald Trump, but Trump won the election because he got “more seats” (if you think about it, the US presidential elections is like a first past the post parliamentary election with MASSIVE constituencies (California giving you 55 seats, etc.) ).

And by looking at the news (and social media), it seems like a lot of Americans just didn’t seem to get it. People alleged that Trump “stole the election” (while all he did was optimise based on the rules of the game). They started questioning the rules. They seemingly forgot the rules themselves in the process.

I think this has to do with the way opinion polls are reported in the US. Check out this graphic, for example, versions of which have been floating around on mainstream and social media for a few months now.

This shows voting intention. It shows what proportion of people surveyed have said they will vote for one of the two candidates (this is across polls. The reason this graph looks so “continuous” is that there are so many polls in the US). However, this shows vote share, and that might have nothing to do with seat share.

The problem with a lot (or most) opinion polls in India is that they give seat share predictions without bothering to mention what the vote share prediction is. Most don’t talk about sample sizes. This makes it incredibly hard to trust these polls.

The US polls (and media reports of those) have the opposite problem – they try to forecast vote share without trying to forecast how many “seats” they will translate to. “Biden has an 8 percentage point lead over Trump” says nothing. What I’m looking for is something like “as things stand, Biden is likely to get 20 (+/- 15) more electoral college votes than Trump”. Because electoral college votes is what this election is about. The vote share (or “popular vote”, as they call it in the US (perhaps giving it a bit more legitimacy than it deserves) ), for the purpose of the ultimate result, doesn’t matter.

In the Indian context, I had written this piece on how to convert votes to seats (again paywalled, it seems like). There, I had put some pictures (based on state-wise data from general elections in India before 2014).

An image from my article for Mint in 2014 on converting votes to seats. Look at the bottom left graph

What I had found is that in a two-cornered contest, small differences in vote share could make a massive difference in the number of seats won. This is precisely the situation that they have in the US – a two cornered contest. And that means opinion polls predicting vote shares only should be taken with some salt.

Nate Silver Interview At HBR Blogs

HBR Blogs has interviewed Nate Silver on analytics, building a career in analytics and how organizations should manage analytics. I agree with his views on pretty much everything. Some money quotes:

HBR: Say an organization brings in a bunch of ‘stat heads’ to use your terminology. Do you silo them in their own department that serves the rest of the company? Or is it important to make sure that every team has someone who has the analytic toolkit to pair with expertise?

Silver: I think you want to integrate it as much as possible. That means that they’re going to have some business skills, too, right? And learn that presenting their work is important. But you need it to be integrated into the fabric of the organization.

And this:

Silver: If you can’t present your ideas to at least a modestly larger audience, then it’s not going to do you very much good. Einstein supposedly said that I don’t trust any physics theory that can’t be explained to a 10-year-old. A lot of times the intuitions behind things aren’t really all that complicated. In Moneyball that on-base percentage is better than batting average looks like ‘OK, well, the goal is to score runs. The first step in scoring runs is getting on base, so let’s have a statistic that measures getting on base instead of just one type of getting on base.’ Not that hard a battle to fight.

And this:

Silver: A lot of times when data isn’t very reliable, intuition isn’t very reliable either. The problem is people see it as an either/or, when it sometimes is both or neither, as well. The question should be how good is a model relative to our spitball, gut-feel approach.

Go on and read the whole interview.