Also looks like Silver's over/under was spot on, maybe slightly underestimated Democrats. Even if that one isn't official, wai was *willing* to bet against that outcome, indicating that he thought it was highly improbable. I wonder if that's led to some reconsideration.
It has.
Nationally, the thing I missed was the independent surge + hard swing of independents against the GOP.
My confidence that Silver was wrong on this particular matter came primarily from early vote data, which Silver deliberately ignores (that's why I beat him 2x in 2016) and which I was keeping fairly close tabs on, e.g., via
these spreadsheets. These data showed serious GOP-voter enthusiasm across many states. In particular, AZ+NC+FL+CA all showed strong GOP enthusiasm---with GOP voters outperforming 2016 as a percentage of the electorate---and strongly suggested the absence of a "blue wave". In my estimation, this enthusiasm is best attributed to the Kavanaugh debacle and Trump's
sui generis ability to keep himself in the media spotlight.
I think my approach was sound for the most part, but I should have compared the percentage of the early voting electorate which was unaffiliated (independent) to historical rates. I don't have time to dig into it now, but I suspect that independents constituted roughly the same percentage of the electorate as in past midterms, or perhaps even exceeded those levels. If that's correct, the astonishing ramp up of GOP enthusiasm to 9/10 in an off-year still wouldn't have been enough to limit GOP losses. In this sense, the national generic ballot's D swing was a key bit of evidence pointing to a blue wave. Silver loves the generic ballot, but for the wrong reasons---distribution of the vote is key, and the generic ballot ignores it. But the generic ballot is super-useful for telling us what independents are thinking, and it appears independents played an out-sized role here.
On a different note, what does it say about independents that they shift reliably against the party in power two years after a presidential election? Would it be fair to characterize these people as perpetually unsatisfied and lacking a coherent worldview? In 2010, they joined the Tea Party people to oppose MOOSLEM Obammer. Eight years later they were eager to #resist the orange man. Independents get a lot of praise, and it's fun to criticize partisans/tribalists from any camp, but at least those partisans appear to have a consistent world-view?