Perusing the results of last Sunday’s German election (thank you, Adam Carr), one thing that jumps out at me is the high–by standards of Germany’s proportional system–disproportionality.
The CDU/CSU won 239 seats, out of a total of 622, for 38.4% of the seats. These parties (which we can, following convention, treat as one in national politics) won 33.8% of the party-list vote. So they had an Advantage Ratio of 1.137. That is rather high, given that the proportionality in Germany is calculated on a national basis. It is higher than the CDU/CSU had in 2005 (1.046) or the SPD in 2002 when it was the largest party (1.081). In fact, not since at least 1969 has the largest party ever had an advantage ratio over 1.10, a level that was reached only in 1990 (the first post-unification election, which was held under slightly different rules). So the CDU/CSU did exceptionally well in this election, beating the limits of proportionality by a good margin.
The greater leading-party advantage ratio is not simply attributable to more below-threshold votes. The combined vote for parties that individually failed to win 5% of list votes in this election was 6.0%, which is not exceptionally high. For instance, the total sub-threshold vote was 5.9% in 1998, although it was lower in the two intervening elections (3.0% in 2002, 3.9% in 2005). (In the last pre-unification election, 1987, it was only 1.3%! Very low sub-threshold shares were typical of the long period of stable three- or four-party politics in West Germany.)
Even without the sub-threshold votes included in the denominator, the CDU/CSU Advantage Ratio would be 1.067, which would remain high for a national proportional system.
Of course, a key feature of Germany’s proportional system is its mixed-member (MMP) character, and specifically its provision for “overhangs.” If a party wins, at the nominal tier of single-seat districts, a number of seats greater than its party-list votes would entitle it to, it naturally gets to keep these extra seats. Seats are then added to the parliament in order to compensate the other parties, but even after compensation the party that has won the overhang keeps some of the advantage. I think of it as a reward for local strength, and thus as a natural feature of a system that is as much mixed-member as it is proportional.
Because of the additional compensation feature, the new German Bundestag will have 323 list seats and 299 nominal-tier seats. The total of 622 is eight more than in 2005 (when the starting point was, as this year, 299 in each tier).
Much of the overhang appears to have resulted from strategic coalitional ticket-splitting: some substantial share of voters chose the CDU or CSU local candidate, but gave their party-list vote to the likely coalition partner, the FDP. Of course, this is by no means the first time we have seen such voting, but the scale of it this time seems rather large.
Consider that the FDP obtained 14.6% of the party-list vote, but only 9.4% of the nominal-tier vote. (I know the list vote is its highest ever, by a good margin, and I am sure the nominal vote is also its highest, but I do not have such votes immediately available for all past elections.)
It is worth noting that this sort of strategic ticket splitting would have contributed to the voter’s favored coalition only if the single-seat district in question would be an overhang for the bigger party. It would be interesting to know whether ticket-splitting was systematically higher in these overhang districts (and perhaps in some near misses), as the strategic coalition splitting argument would imply (at least if we assume voters are sufficiently informed to know the shape of the contest in their own district).
So the likely next government of CDU/CSU and FDP will be formed by parties that won a combined 48.4% of the list votes and 48.8% of the nominal votes. Not much difference there. It will have 332 of the 622 seats, or 53.4%. Even if we (inaccurately) treated all of this vote as a joint governmental vote, we would still have an advantage ratio of 1.103. I do not know how that compares historically, but it must still be on the high side.
Did the overhang seats make the difference between a CDU/CSU + FDP majority and a “hung” parliament? I do not think so, but it was a close call. I hope others who have followed the German election can offer their insights on this “disproportional” outcome. (Again, disproportional only in the context of Germany’s highly proportional rules.)