Should French pollsters be using Mister P?

An anonymous statistics student from France sends in the above plots (click twice to see big versions) and writes: I’m trying to push French pollsters to start doing MRP. I made a poll agregator and applied it to the last 100 days of the last five french presidential elections. I did some smoothing using an algorithm from a paper of Aki Vehtari. It is Kalman-RTS with cross-validated levels of noises. I tested it on some simulated data to confirm it is fitting properly. I put the data and the code on my blog. What I shared as “the data” is the smoothed result. I fitted it on the wikipedia pages of the french polls. On the plots, the same parties (with changed names or fusions) are on the same position horizontally to allow comparisons. I see some periodic movements in opinion that I think may be coming from a periodic non-response. Also, the movements seem far too large to me. I can believe 10% increase for a candidate in five years, but not in less than 100 days. The French polling…