Archive for Italy

An Exercise in Elementary Statistics: Application to Italian Electoral Polls

Posted in G 1 with tags , , , , , , on March 27, 2008 by Roberto Gravitazero


As political elections in Italy are getting close, several blogs and sites are publishing predictions, especially about the outcome at the Senate where, thanks to the peculiar electoral law, it is well possible that no clear majority would emerge.

So, I could not resist to make my own prediction. And I start by giving you the results:

PdL PD SA UDC Others
162 131 17 4 1

Which is indeed a very close call, possibly not enough for PdL in order to rule the country. Berlusconi would have only four seats more than the ones obtained by Prodi in the last elections. Who, however, had initially on his side all of the 7 senators nominated for life by the President, and not counted above. Actually, he got 165 favorable votes when he formed his government in 2006.

I should warn you however that I would be very surprised if this prediction will be exactly fulfilled, and I’m going to tell you why. But, before that, I should explain how I got the prediction in the first place. The method is the one developed by Sandro Brusco from noiseFromAmeriKa. Essentially, one takes the results of 2006 (Senate, divided by Regions), and re-normalize them using the ratio between whatever pre-electoral poll one is trusting and the global results (for the lower chamber) in 2006. Technically, a so-called uniform national swing is assumed. Simple, if not at all granted. But the main complication is how to take into account the different political alliances of 2008. For that I have used a slightly different logic than Brusco (for instance, differently from him, I had allocated UDEUR votes half to UDC and half to PD, while I counted for PD only half of the votes of the former alliance between Radicals – now with PD – and socialists – now independent). There’s more to it, but it does not amount to a large effect in the end. I have checked against Brusco system, using data from the last 7 polls. In 5 cases I obtained the same seats than him for PdL, while in 2 cases I had 2 and 4 seats less, respectively. A result that in my mind reflects well the quasi-chaotic behavior of the system.

In any case, my prediction above is obtained by using an average of all published polls from the beginning of March to the 26th (from Toqueville), a grand total of 41! Now, having taken care of the first order, and being a physicist, I could not refrain to have a look at the whole distribution. Here it is:


In the histogram the bars show how many times (out of the 41 samples) PdL had obtained in the simualtion a given number of seats, while the line indicates the cumulative percentage of the total samples below a certain number of seats. For instance, about 50% of the times PdL totalized 162 seats or less. The standard deviation is almost exactly 4. Now, I believe this information adds a lot to the bare prediction. If the polls are correctly done, if the hypothesis of a uniform national swing is correct, and if I have made no additional mistakes, the conclusions are:

1) It will indeed be a close call.

2) No need to discuss about a difference of plus or minus 4 seats in the predictions for PdL – one cannot possibly be more precise than that.

3) It’s quite likely that the situation in the senate will not be better for Berlusconi than it was for Prodi in 2006.

A couple of additional remarks:

noiseFromAmeriKa, like other sites, uses for its prediction an average of the last “few” polls, in order to better reflect the evolution of the public opinion. However, the spread between different polling institutes and individual polls is larger (at least since the last month) that the variation of the average, as one can see in the following picture, showing the simulated number of seats for PdL obtained for the different polls:


The line is a second order fit. The evolution of the average is negligible. However, if anything, it looks like the standard deviation is decreasing (especially discounting the 14 March MAKNO poll, really sticking out from the rest and with a low statistical coverage – less than 400 interviews). I have no idea of what this means. It could be a stabilization of the vote towards the smaller parties (there’s no evolution visible it the bare percentage for PdL, as shown below), or, one could mischievously suspect, a tendency of the polling institutes to uniform their results with each other.


The last plot shows the correlation between simulated number of seats and the percentage of votes in each poll, again for the PdL. As pointed out already by Brusco, the correlation is small compared to the spread, showing the impact of the distribution of the remaining votes among other parties. It shows as well that even exceeding 45% of the votes, the PdL could not be sure to obtain a clear majority.


I conclude with a warning: the hypothesis of a uniform national swing is far from being sure. There are reasons to believe that local factors could result in an uneven redistribution at the regional level, and the electoral rules makes the system very much sensitive to this. On top of that, in 2006 the pre-electoral polls had been shown to be not exactly reliable. Therefore, anything can happen. It’s well known it’s not easy to make predictions, especially about the future.

Hat tip to Dorigo, to whom I’ve stolen half of the post title.

Update 30 March – many pre-electoral polls have been published just before the black-out (no polls during the last 15 days before the elections). Using the average of all polls (now there are 50 of them), the prediction does not change. I did also an update of the distribution, which I show below. Note that the lowest (156) and two of the highest (172, 173) predictions are from one month old polls(1,2 and 3 March). The other high one (174) is the Makno one I talked about above. I would tend to exclude them, and I report them here only for completeness.




What is the right choice? Anyone left?

Posted in G 1 with tags , , , , , on March 22, 2008 by Roberto Gravitazero


I don’t know. I mean, I don’t know yet for whom I will vote at the next Italian elections.

And of course I know even less if finally my choice will be the right one. I bet many, who are leaning to the left as myself, are in the same situation.

But if you are like me an Italian abroad, you can find an interesting hypothesis in the blog Scandinaria. A good exercise in games theory, if you like. In short, one way to maximize the gain for the left as a whole, in the European constituency, could be a split vote: PD at the senate (no chances anyway for other parties of the left to elect a senator), and SA (or IdV) for the chamber of deputies (where, with more places available, small parties could take out some from the right).

One other important point is that the electoral rules are specials for Italians abroad. If we don’t have the portentous flexibility one can have in French local elections, we’re still free to choose between candidates, and not only between parties like our countrymen at home. So, whatever your choice, use your vote to select among the candidates. So far so good.

But life is all but perfect. And so it happens that the one I would consider a very good candidate, Beatrice Biagini, is in the PD lists for the chamber of deputies, and not the senate.

I have actually never met her. But I happened to stay as a host in her place for a couple of days (while she and her husband were absent), when visiting a couple of common friends in Paris. Nice cozy house, as that, and lots of interesting books. The matter is, anybody who’s willing to lend her house to a virtual unknown, and reads these books, has quite a head start as far as my vote is concerned.

So Scandinaria did not completely solved my doubts. Thanks anyway, guys, it was a good try.

P.S.: In order to respect the par condicio rule, I insert as well links to a candidate from the right. No, I don’t think I’ll vote for him, though.

A phone call you can’t refuse

Posted in G2 with tags , , , , , on March 17, 2008 by Roberto Gravitazero


Mentioned in Massimo Morelli blog, I’ve found a noteworthy article published in Time by Roberto Saviano, in which he talks about the Mob influence on political life and elections in Italy. Saviano is a journalist, renowned for his best-selling book Gomorrah in which he exposed the activities of the Camorra (Naples mafia-like crime organization). He now lives under police protection. I recommend the article not just to non-Italians willing to better understand our country, but to Italians as well. It’s remarkable how I keep finding the most objective and informative pieces of informations on Italian politics in foreign newspapers. I report below an interesting passage:

Too many elections in Italy are won, even today, by the time-tested process of buying votes. It is an especially formidable weapon in the south, where high unemployment is so endemic that many ambitious young people emigrate to the more prosperous north or abroad. When I was a kid in the 1980s, an individual’s vote tended to cost more than it does today. It might have been worth a job at the post office, say, or in public administration or a school or hospital. By the time I grew up, votes were typically sold for far less: telephone and electricity bills paid for the two months before and one month after an election. In the last few ballots, the new bait has been the cell phone. Someone shows up and gives you one before the election, and you can keep it if you come back with a photo on this new, shiny handset showing your ballot marked for the right candidate. The phones, which are worth about $75 apiece, are even conveniently set up to snap the pictures silently. The fluctuating value of a vote seems to have returned to its level in the 1950s, when the businessman-mayor of Naples, Achille Lauro, offered packs of pasta and a new left shoe before an election. The right shoe could be collected afterward upon proof that the correct choice had been made.

I had many occasions to despise and condemn the inordinate passion shown by my fellow countrymen for cell phones.

One more reason to continue to do so.

À la carte

Posted in G 0 with tags , , , on March 9, 2008 by Roberto Gravitazero


Today I had the ineffable pleasure to vote for the local elections in France. Well, maybe I’m exaggerating a little bit, but it was indeed a pleasure.

I don’t know how familiar is the average reader with the French electoral rules. I thought I knew them reasonably well, but I must admit until this week I wasn’t aware of the peculiar way in which one exerts his electoral rights in a French municipality with less than 2500 inhabitants.

It works like that: You are given a few sheets of paper, each one containing a list of candidates from different coalitions (in my case there were three of them, all local coalitions, with no explicit references to national political parties). You are supposed to vote by putting one of the lists in an envelope (for secrecy), and put the envelope in a box. So far so good, nothing really special.

But you should know that you’re allowed to erase from the list any name you don’t like. Now, this start to be interesting (I can imagine some of you are already fantasizing), but that’s not the whole story. You’re allowed as well to substitute them with candidates taken from the other lists, or even with names of people outside any list. In fact, you can actually write a list of your own, if you fancy it, with the names of the fellow citizens you deem most worthy of being part of the “Counseil Municipal”.

Well, these are very local elections, and maybe is not really fair to make comparisons, but I could’t avoid to think about the differences of such a system with respect to, say, the present Italian electoral law.

Yes, as an Italian abroad, I will soon be called to vote for the next political elections. And, guess what, I fear I will not experiment exactly the same feeling of pleasure.