A tied poll in FL-22 leaves our forecast where it was

One new poll of Florida's 22nd District has the race even. Tavern Research surveyed 551 likely voters on August 10-12 and found the Republican and the Democrat at 50 percent each.

Our forecast did not follow it. As of 12:03 PM ET on August 21, our model gives the Democrat a 97 in 100 chance in FL-22, with a mean margin of D+19.2 and a 5th-to-95th percentile range running from D+2.2 to D+36.2. The run before it, at 10:30 AM ET, had the same 97 percent and a mean margin of D+18.9. The Republican's chance stands at 3 percent, unchanged.

That gap between a single tied survey and a double-digit projected margin is worth stating plainly. Our model weighs district-level polling against everything else it uses, and one poll of 551 voters moved the mean margin by three tenths of a point in the Democrat's direction — not away from it. The wide interval is where the doubt lives: the bottom of our range is a Democratic margin of about two points, so a close result is inside what the model considers possible even at 97 percent.

Nationally, our average of 24 generic-ballot polls over the past 45 days sits at D+6.7. Our model gives Democrats a 94 percent chance of winning House control, with a mean of 242.5 seats against the 218 needed. One caveat on that number is ours, not the data's: our simulation draws correlated error nationally, by census division, by state and by district, but we have no cluster data to correlate demographically similar districts across regions. Without that term, the House control probability is marginally firmer than it would otherwise be.