Nate Silver

Nate Silver @NateSilver538

RT @kwcollins: Not only is prioritizing by age good on the merits, it's also helpful politically, because it's a well-defined bright line t… — PolitiTweet.org

Nate Silver @NateSilver538

There's going to be a **lot** of this happening if you define a very broad set of preexisting conditions as deserving higher priority for vaccines. It's a huge, avoidable mistake. https://t.co/vWE5xTTKGK https://t.co/sZesgR1I2n — PolitiTweet.org

Nate Silver @NateSilver538

But ACIP defines *more than 100m people* as having "high-risk medical conditions" that put them in the same priority tier as people age 65+ for vaccination. This is NOT following the science. States that want to save lives must give age higher priority. https://t.co/mdccG7VHXl https://t.co/iFit37Kd74 — PolitiTweet.org

Nate Silver @NateSilver538

If you look at the research, virtually all of people at highest risk of dying from COVID are aged 70+. There are almost no preexisting conditions that matter remotely as much as age. https://t.co/xlbGJb25OF https://t.co/c9KjUpc80r — PolitiTweet.org

Nate Silver @NateSilver538

At least with essential workers—if you can define the scope narrowly—there's an argument to be had about reaching herd immunity sooner. What will literally kill people is treating a broad set of preexisting conditions as being as important as age. — PolitiTweet.org

Nate Silver @NateSilver538

Also sort of interesting that the final impeachment polls (+4 pro-impeach) very closely mirrored the eventual election result, more closely than Trump's overall approval numbers did. https://t.co/Tj71WyGT4x https://t.co/Q5zN3g9dMc — PolitiTweet.org

Nate Silver @NateSilver538

It sort of got lost in the news cycle because the pandemic hit soon afterward, but it's worth noting that Trump's approval rating generally improved over the course of the impeachment process, especially after his acquittal by the Senate. https://t.co/Vfmzd6B2ps https://t.co/0tHGB5gMVg — PolitiTweet.org

Nate Silver @NateSilver538

In New York City—which has good data on death rates by age—people age 75+ represent 6% of the population but *49% of COVID deaths*. This is a no-brainer. If your plan doesn't prioritize people in this group, you screwed up and need to start over. — PolitiTweet.org

Nate Silver @NateSilver538

At the very least, define these categories *narrowly* with some sort of empirical basis. If there are 87 million "essential workers" (as per ACIP) that's not a very useful category; that's more than half the working population in the US (~160 million)! — PolitiTweet.org

Nate Silver @NateSilver538

The other key point here (as @mattyglesias pointed out in his newsletter today) is that both "pre-existing conditions" and "essential workers" are highly amorphous categories that will be gamed (especially by the rich and powerful) whereas age is not. — PolitiTweet.org

Nate Silver @NateSilver538

This story is much better than the headline but the people who *really* made a killing off Gullible Trump Supporters weren't the offshore oddsmakers but people who've bet on Biden because they're grounded in something at least vaguely resembling reality. https://t.co/TF7cXjSsFG — PolitiTweet.org

Nate Silver @NateSilver538

Anyway! We're pretty happy with these changes, though we may take a longer, fuller look at RAPTOR this off-season when the system has 2 years under its belt and we have a full off-season to work with. In the meantime, we hope you'll enjoy our NBA coverage. Thanks, all. 17/17 — PolitiTweet.org

Nate Silver @NateSilver538

Conversely, if there's a lot of turnover in the lineup because of injuries, trades, etc., looking at past team performance may not tell you very much. Instead, the projections will gravitate very heavily (in some cases 95%+) toward RAPTOR. 16/ — PolitiTweet.org

Nate Silver @NateSilver538

How do we weigh the RAPTOR component vs. the Elo component? It depends on how much continuity there has been in a team's lineup. If a team has high continuity, then team performance really does tend to be more robust so Elo may get 50% or more of the weight. 15/ — PolitiTweet.org

Nate Silver @NateSilver538

Another change is that a team's rating will now reflect a combination of its RAPTOR rating and its Elo rating. Elo, if you'll remember, is a purely TEAM-BASED measure, and it tends to put more emphasis on recent games. 14/ — PolitiTweet.org

Nate Silver @NateSilver538

So one change we've made is to now use RAPTOR for in-season adjustments. While our preseason projections did quite well last year, the in-season updating was pretty clunky, if I can be frank, leading to some... weirdness by the playoffs, and this should help with that. 13/ — PolitiTweet.org

Nate Silver @NateSilver538

PREDATOR may nonetheless be better than RAPTOR for forecasting a player's performance in *future* seasons. But we were also using PREDATOR to account for a player's *in-season* performance and adjust his team's rating on that basis, when RAPTOR works better for that. 12/ — PolitiTweet.org

Nate Silver @NateSilver538

But if you're forecasting how the Rockets are going to do when both Harden + Russ are still in the lineup, that's less of a problem. Under RAPTOR, the errors literally cancel out. Thus, RAPTOR itself is a TEAM-BASED rating in certain respects, whereas PREDATOR isn't. 11/ — PolitiTweet.org

Nate Silver @NateSilver538

One issue with RAPTOR and other +/- systems is they can sometimes misallocate credit between teammates. So e.g. maybe they had Harden too high and Russell Westbrook too low. If you're forecasting how they'll do now that they're on separate teams, that could be a problem. 10/ — PolitiTweet.org

Nate Silver @NateSilver538

Additionally, RAPTOR includes an important property that PREDATOR does not. Basically, it works backward by starting with the team's performance and forcing the player ratings to sum up to the team rating. In PREDATOR this assumption is relaxed. 9/ — PolitiTweet.org

Nate Silver @NateSilver538

But what works best for projecting *player* performance may not be optimal for projecting *team* performance. Or at least, that's what we believe after looking at the problem this winter. What looks like "luck" to PREDATOR may really reflect a player's role with the team. 8/ — PolitiTweet.org

Nate Silver @NateSilver538

PREDATOR was trained by looking at out-of-sample performance, especially for players who switch teams. So e.g. if Harden is traded to the Heat, PREDATOR would theoretically give you a better idea of his performance than RAPTOR. 7/ — PolitiTweet.org

Nate Silver @NateSilver538

This gets a bit technical, but there are actually two sets of ratings we run for each player. One is called RAPTOR, which is what you see in the interactive here. But there's also a related system called PREDATOR or "predictive RAPTOR". 6/ https://t.co/uKS6KENaGJ — PolitiTweet.org

Nate Silver @NateSilver538

What's really best, though, *especially* for updating your ratings as the season goes along, is some sort of hybrid between TEAM-BASED and PLAYER-BASED. Whereas what we had last year was sort of on the extreme end of PLAYER-BASED with little/no team component. 5/ — PolitiTweet.org

Nate Silver @NateSilver538

If you had to pick one or the other, the PLAYER-BASED projections will generally be stronger. Even though basketball is a team sport, you just lose too much accuracy if your projections don't immediately account for, say, James Harden getting traded (if he gets traded) 4/ — PolitiTweet.org

Nate Silver @NateSilver538

Alternatively, PLAYER-BASED projections work by summing up the projections for individual players, e.g. by using our RAPTOR ratings. That is, team performance is assumed to be ~equal to the sum of the parts. This has the opposite set of strengths and weaknesses. 3/ — PolitiTweet.org

Nate Silver @NateSilver538

In the past, we've really used two ways to project NBA games. One is TEAM-BASED solely using team performance, e.g. via Elo ratings. Advantage: captures team "intangibles" (coaching, cohesion, recent form) Big disadvantage: doesn't account for player personnel changes. 2/ — PolitiTweet.org

Nate Silver @NateSilver538

As @Neil_Paine talks about here, we also made a couple of important changes to our NBA projections this year. I'm going to simplify this a bit, but basically it comes down to PLAYER-BASED projections vs. TEAM-BASED projections. LONG DORKY THREAD 1/ https://t.co/8n1tUWeg0T — PolitiTweet.org

Nate Silver @NateSilver538

The Lakers are the most likely champions, although it's a fairly wide open year. Our projections assume that teams will need to rely more on their depth in the regular season because of COVID-19 complications, which could scramble the standings a bit. https://t.co/6AImvBFJqB — PolitiTweet.org

Nate Silver @NateSilver538

Hey folks! We've got our NBA team and player projections ready for 'ya. https://t.co/i3U5UyC3sA — PolitiTweet.org