With just under seven months to go until the German federal election, I have recently begun once more to pool the pre-election polls from seven major survey firms. Since January, when the date for the election was set and the Spitzenkandidaten were selected, results from 35 polls with a median sample size of about 1900 have been published: nine apiece by Emnid and Forsa, five by Dimap, five by Insa, four by FGW, two by Allensbach, and a single one by GMS.
Easily the most exciting event in the (long) campaign so far has been the #Schulzzug: the mostly unexpected leak/announcement on January 24 that Sigmar Gabriel would be replaced as party leader and (presumptive) candidate by Martin Schulz, the former president of the European Parliament. Support for the SPD in the polls had hovered at historically low levels of just over 20 per cent for months, but the Schulz candidacy re-energised party members and resulted in lots of (mostly positive) media coverage so far. Subsequently, support for the party leaped up in the polls, even overtaking support for the Christian Democrats in some of them.
But most movement in the polls is noise, and so we would like to know if the Schulz bounce is real. The data basically say: yes.
The figure shows that support for the SPD begins to rise a couple of days before Schulz’s candidacy was announced, but this is probably an artefact. The model assumes that true support normally changes very little from one day to the next, but these are unusual circumstances, and so the ascent was probably steeper than the graph suggests. At any rate, the estimated level of support for the SPD in February was somewhere between 30 and 35 per cent, whereas it was between 20 and 24 per cent early in January. The model’s priors may play a role here (though they should be quickly overwhelmed by the data), but it is obvious that there was a gap of at least 10 percentage points between the two major parties in January that has essentially closed now. Support for the CDU and the SPD is virtually indistinguishable, and the Christian Democrats are rightfully worried.
What this means for the election is a different question. Estimated levels of support for both parties have been essentially constant for the last four weeks or so. The SPD has unexpectedly closed the gap, but it has stopped gaining. The Christian Democrats are not doing much worse than at the same point in the cycle four years ago. And once voters learn more about Schulz (who is a known unknown in Germany), the Schulz effect may wear off.