The results of today’s Italian election were… a little different to what I predicted, and to what most people expected. It seems that the M5S was able to pull off an astonishing upset, draining votes from the centre-left, and becoming Italy’s largest party.
I’ll have to look at how and why the polls were so wrong. In the meantime, I thought it would be useful to take a look at some summary stats, and ask: how can we put this result into context?
One way is to use a measure of volatility between elections. Although the measure has been criticised for mixing (a) volatility due to party entry/exit and (b) volatility due to shifts between parties, Pedersen’s index of volatility remains the most commonly used measure.
On this measure, and looking at consolidated Western European democracies (other parliamentary democracies, i.e., those in Central and Eastern Europe, get by with higher levels of volatility), Peter Mair (whose posthumous festschrift was held today at the EUI) compiled this list of volatile elections:
|Country||Year||Level of Volatility (%)|
This table is built on the basis of certain assumptions. It’s very difficult in a fluid environment to say which parties are really continuations of previous parties, and which are splits. Consequently, tallies of volatility differ.
But if you accept the calculations in this spreadsheet, then Italy 2013 comes out on top of this list, with a Pedersen index of 39.04.
That means that this result is a bigger event (in some senses), than the Dutch elections of 2002, held shortly after Pim Fortuyn’s assassination. And bigger than the 1994 election, which signalled the end of the First Republic. Without wishing to sound too pompous before the votes have been fully tallied, it’s elections like these that bookend historical periods in a country’s history.
@chrishanretty Spain 1982 also a biggie.
— jonathan hopkin (@jrhopkin) February 25, 2013
I make it out to have a Pederson index of 38.345 based on the top six parties, but don’t have full election report to hand, so it might tip over.
Pedro Magalhães tweets to say that Greece May 2012 is higher, at 42.3.