One more "PS" to Jun Okumura's comment on my post (and Paul Midford's) about PM popularity effects. It occurs to me that the PR tier votes is not the only way to measure PM effect on voting. It's even more complicated because with the SMD tier and one representative in each district there is a greater identification of the individual representative with his or her political party, including that party's leader's image.
Previously under SNTV before reform because of multiple LDP candidates running in most districts, the "personal vote"
really was a personal vote for the candidates themselves. Now, party image, party policy,and party leader image are more connected to the individual representative's personal appeal and more difficult to sort out the motivation for the vote.
Best regards,
Ellis