Psephology /sᵻˈfɒlədʒi/ (from Greek psephos ψῆφος, 'pebble', as the Greeks used pebbles as ballots) is a branch of political science which deals with the study and scientific analysis of elections.
Found this while reading an article in The Economist. The whole sentence was: "But Sir David Butler, a nonagenarian psephologist at Oxford University, noted on Twitter that in the 20 general-election campaigns he has followed, “I can’t remember a U-turn on this scale.” "
A nonagenarian is a person who is from 90 to 99 years old.