Is Grexit really possible? Poll data and greek elections forecast

   On Sunday Jan 25, the parliamentary elections in Greece will take place. Today the Greek political field consist mainly of all shades of red and brown, and some recent polls shows the left-radical party SYRIZA may get the majority (151) of seats in parliament in a result of the upcoming elections. However, every poll has a margin of error, and individual poll results can be outliers. To make more reasonable estimate, it is better to use average data from all surveys conducted from January 1 by different polling firms that were collected on this Wiki page.

According to the forecast, most likely, SYRIZA will get 146 seats in parliament, which would not give it an absolute majority, but will give an opportunity to get a majority in coalition with some of the smaller parties.

   Such a possibility worries observers who fear a sharp reversal of Greek policy towards rejection of the Euro currency and exit from the European Union (so called Grexit), despite the fact that SYRIZA leader Alexis Tsipras recently stated that it has no such plans.

Notes:

1. To obtain results comparable to other polls and the official election results, the raw data of the polls has been adjusted based on the simple rule of three, which mean the "group of undecided and/or abstaining voters" have been assumed ultimately to cast their votes (if any) according to the exact same distribution as the group of decided voters (having cast a specific vote in the survey). Or in other words, they are simply disregarded under the assumption they will not cause any change to the already found distribution of votes. After this calculated adjustment, the total of all noted vote shares equals 100%, which is similar to how the results of the official elections are presented. This practice is done for most pollsters, as most of them use and/or have used this system in the past in order to show results comparable to other polls and election results.

2. Avaliable data of polls was averaged for each poll date in the case of several polls on one date. The raw data used and the links to original data from polling firms can be found on corresponding Wikipedia page.

3. Forecast is linear trend extrapolation of averaged data to election date (25/01/2015).

4. To obtain forecast for parliamentary seats Greek operating rules of distribution of seats among elected parties should be taken into account. 250 (of 300 overall) seats distributed on the basis of proportional representation, with a threshold of 3% required for entry into parliament. Blank and invalid votes, as well as votes cast for parties that fall short of the 3% threshold, are disregarded for seat allocation purposes. 50 additional seats will be awarded as a majority bonus to the party that wins a plurality of votes, with coalitions in that regard not being counted as an overall party but having their votes counted separately for each party in the coalition, according to the election law.