India’s Election Exit Polls: Counting Pebbles!

Credit: MathPickle

A nation of 1 billion, India, is counting its votes on May 23 to see who the next leader of the world’s largest democracy will be. Until then, it’s anybody’s guess. Or is it?

In actual fact, there’s a group of people who specialize in scientifically estimating trends in voting and the results of elections and they’re called psephologists. Yes, you heard right. Originating from the Greek word psēphos which means pebble or vote, it dates back to the time citizens of the first democracy in Athens cast their votes by throwing pebbles into one of two urns.

What is an exit poll? Psephologists in India have been busy during the last month of elections conducting exit polls in several constituencies all over the country. An exit poll essentially surveys a random sample of voters on their way out from the booth and asks them who they voted for.

Different organizations conduct exit polls in different ways and unfortunately, they don’t always disclose their methodology. While sample sizes have been increasing with every election and the 2019 election has the largest sample sizes on record, the accuracy of an exit poll is not always related to sample size.

Why’s that? Stratifying the sample so that it is representative of the community’s demography is more important. Interpreting the data from the exit poll and translating sample voting results into seats for each party also requires significant statistical, political and sociological expertise.

So how reliable are the exit polls? If they rely on biased samples and inaccurately translate sample vote shares into seats, the exact numbers are sure to be off. However, if the exit polls show that one party has won an overwhelming majority, you could conduct some amateur psephology yourself and reduce their seats by say a 20% margin of error and see if the same party still wins.

So which urn will be heavier on May 23? Wake up early and see for yourself if the psephologists got it right!


Written by: Shonar Lala Chinoy