The dataset contains information on the electoral alliances in Finnish parliamentary elections formed between two or more parties in 1945-2007, sorted by electoral districts. The data have been collected from the Statistics Finland's parliamentary election data.

The advantageousness of the electoral alliances in the data was examined by splitting each alliance in each electoral district one by one, and by calculating whether the parties participating in them would have received more, as many or fewer seats in the parliament if they had remained unallied in the elections. The basic assumption behind the calculations was that each party participating in the alliances would have received an equal number of votes if they had been unallied. If the electoral alliance had been advantageous to at least one of the parties involved, and simultaneously disadvantageous to none of them, it was calculated which of the parties involved would have received the seat received by the alliance, in case the alliance in question had not existed.

The dataset contains information on the parties involved in the electoral alliance, on the advantageousness and disadvantageousness of the alliance, on the disadvantageousness of the alliance tothe parties not involved in the alliance, on the electoral district of the alliance, and on the number of seats in the electoral district.