Especially since it both is and is not in cup until you try to taste it. And then the foam collapses.
Stuff like this is what keeps me hanging around this place. 
In response to the OP I don’t think the rating has really fallen. The 538 approval is 41.4 which is around where it has been for 18 months. 538 has some nice charts comparing Trump’s ratings with other Presidents and it’s remarkable how stable they are. Possibly that is because they have always been on the low side thus having a large percentage of his solid supporters plus the fact that there hasn’t been a truly major event like a recession or a war.
Just about the only change was from late 2017 to early 2018 where the rating went up from around 37 to 41.I have not seen a good explanation for why his rating went up around that period. I think figuring out who those 37-41 voters is an important and underexplored question. These may be voters who approve of him but could be persuaded otherwise, at least to not vote for him . Perhaps if the economy slows down, as many people expect, they will move away from him on their own. However a well-run Democratic campaign should examine this group and tailor at least a part of the campaign message to them.
I noticed that the ratings took a dip in late August of all three years and wondered if that meant anything (just in terms of patterns in the noise or of poll seasonality) as I couldn’t think of actual political reasons for that (and all three dips are really within noise bounds). My personal unscientific threshold for thinking “something’s changed” in the last year of fivethirtyeight polls would be more than a week of either “above 43” or “below 41” which we haven’t hit, but the movements that were traceable to events and not noise moved at least that much.
I think the “37 to 41” rise that Lantern mentions is due to the tax cut going through?
Yes the rise happened around the time of the tax cut but IIRC the tax cut was not all that popular so I wonder if it really caused just about the only permanent change in Trump’s approval in the last 2.5 years. OTOH 4 points is not that much;perhaps it only seems significant because his ratings have otherwise been so remarkably stable.
I explained what relevance it had and what time period I was looking at in post 29. Here’s an excerpt.
Over the time period of the drop that inspired this thread, Rasmussen showed a significant drop, while the average of all other pollsters moved in the opposite direction.
I noticed this many times during the year I’ve had this Twitter robot tracking Rasmussen v the field. When people ask, “Why is Trump’s favorability doing X?” I check my graph and frequently notice a very steep section on the Rasmussen line that matches the shift that led to the question.
e.g..
Check out 1/25 to 2/22. These are approximate from eyeballing the graph.
Rasmussen net 1/25: -10
Rasmussen net 2/22: 0
Net net: +10
non-Ras net 1/25: -14
non-Ras net 2/22: -12
Net net: +2
Now look at 538 for the same period.
538: -16.7
538: -10.3
Net net: +6.5
A huge shift in Rasmussen accompanied by a slight in shift in everyone else corresponds with a modest shift in 538’s tracker.
Finally, of course a single pollster is noisier than the average of all other pollsters. However, Rasmussen polls 500 *likely voters every single day and reports a three day rolling average every day. My graph shows a 14 day centered rolling average of those 3 day averages.
In the graph I posted originally we see Rasmussen’s Trump net fairly steadily go from +1 to -6 from mid-June to mid-August while the average of all other pollsters stays pretty much level over the same period. The explanation, “One pollster will always be noisier than the average of all other pollsters,” is not even in the ballpark of being sufficient to explain this.
*Likely voters means that they poll more than 500 voters a day and throw some/many out depending on how strict their likely voter screen is.
Lance Turbo, I will state this unapologetically. As Carnal K’s excerpts of your posts makes clear your “point” has contradicted itself several times. In any case the data you present supports none of those positions.
How about we start with what we most likely agree on?
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The true signal of Trump’s net approval is very flat. 538’s tracker is likely the best we can use as a gold standard and it has been within 2 of 12 one way or the other over 95% of the time for a very long time.
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Individual polling houses will be noisy and aggregation cancels out much of the noise. This is true if the aggregation is all polls equally weighted, or filtering out a single house, or 538’s more sophisticated method.
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538’s more sophisticated method is not a completely black box. We know that it discounts results from houses that report prolifically (like Rasmussen) to a degree that they count no more than a similarly rated house that reports once every 20 days. We know that they discount poorly rated houses like Rasmussen (C+) and more heavily weight A to B+ ones, like IBD, Quinnipiac, Ipsos, CNN, Suffolk, Monmouth, NBC/WSJ, and Fox.
So far so good I hope.
Now let’s look at those highly rated houses that are most heavily weighted in the 538 tracker, most recent to its next most recent, net approval changes. Time period for most is about a month some six weeks. As reported on 538.
IBD flat (A+)
Quinnipiac dropped 4. (A-)
Ipsos dropped 1. (B+)
CNN dropped 7. (A-)
Suffolk dropped 11! (B+)
Monmouth dropped 3. (A+)
NBC/WSJ dropped 2. (A-)
Fox dropped 8. (A)
Average of these highly rated houses that are weighted more highly in the 538 tracker was dropping about 4.5 over the 4 to 6 week period that is roughly concurrent with the 538 tracker going down by about 2.5, from top of the range back to lower middle.
The highest rated houses as a group dropping back to the mean clearly are what drove the drop in the 538 tracker. Softened some by the greater sophistication of that model than my crude averaging them alone and equally.
Rasmussen was immaterial and of very little input to that tracker as should be the case. None of us know what exact weight a C+ rated house gets but if it is not extremely light I’d be shocked.
I will state this unapologetically. You are incorrect.
My opinion is that a big Rasmussen swing can shift the 538 average. I have presented data that supports that, and shown that it is a recurring phenomenon.
You are free to disagree.
I rise to speak on behalf of the Board Committee for the Hopelessly Mathtarded. As fascinating as this conversation has been, we can’t help but feel that it would be even more interesting if we had a clue. Any chance you guys could plaly this game “slow-pitch”?
Sure. Look at the red and blue lines in this picture. The red line shows a large drop in Trump net job approval. The blue line does not. Is the opinion that red line was more responsible for the drop in Trump net approval than the blue an unreasonable opinion?
Ok, I’m not a Data Scientist so could you explain why it’s only “almost” all the variations in the difference line are caused by Rasmussen? I mean, to this layman, you are plotting how different Rasmussen is from the average so I would think Rasmussen is entirely to blame for every variation from the average.
Yes Lance Turbo, I am free to disagree.
More accurately though Silver’s description of how his model works and the data showing that the move of his tracker moves most in concert with the higher rated houses’ movements as a group is free to disagree.
A single C+ pollster simply cannot move the 538 tracker by any significant degree, no matter how big of an outlier they are. And his poll does not follow the average of all polls published equally weighted either.
You are free to be wrong. 
Slow pitch, as best I can …
Silver’s model counts all polls but in Animal Farm fashion some polls are more equal than other polls. A C+ pollster gets very little weight. A pollster does that publishes every day does not increase its weight over a similarly rated pollster that releases once every 20 days. As a C+ pollster Rasmussen has very little impact on 538’s numbers, much less than an A+ to B+ pollster that publishes every 3 weeks, no matter how often they publish results. The group of those top rated and heavily weighted pollsters are what drive 538’s numbers significantly, and their average change from most recent to next most recent is what drove the (insignificant) “drop” noted by the op. The average of all polls published equally weighted has nothing to do with how the 538 model works.
Lance Turbo seems to think that because sometimes Rasmussen’s noise goes the same way as the 538 tracker (mostly driven by the top level houses, not by his Blue line all non-Rasmussen polls) goes, (and of course sometimes the opposite direction too, even within his sample graph) it means that Rasmussen MUST drive the results. It’s a pretty absurd conclusion.
What I was trying to say was in the graphic that I made and linked to, the red line line moves up and and down a lot, and the blue line doesn’t move up and down much at all. This means that the the green line moves up and down a lot due mostly to the red line and not the blue line.
That’s a pretty indisputably correct description of that graphic.
This is likely incorrect. Even a pollster that has a lower weight can probably move the model with a large enough swing. In particular they could do so when all the other pollsters, on average, are basically static. It has nothing to do with Rasmussen being an outlier and everything to do with Rasmussen trending massively and differently than the average of other pollsters over long periods of time.
This is also incorrect. I have taken steps to remove the day to day noise in the Rasmussen data so I could better capture how Rasmussen trends compared to the average of all other pollsters. Furthermore, my conclusion is not that Rasmussen MUST drive the results. I have presented a hypothesis and data that supports that hypothesis. I certainly could be wrong because my hypothesis relies on unverifiable assumptions about the 538 model.
DSeid thinks my assumptions are incorrect. DSeid is also making several unverifiable assumptions about 538’s model which I think are incorrect.
Also I am not claiming to have proved that Rasmussen is solely responsible.
I am guessing that Rasmussen is noticeably responsible. My guess, which may be wrong, is backed up by evidence.
Mostly I just wanted to share my sweet-ass Rasmussen tracker Tweet-bot.
Since no one asked, I’ll tell you a funny story about that tracker. This is in no way intended to bolster my argument in this thread. It’s just an amusing anecdote.
One afternoon I did not check Twitter for a few hours and was shocked to open it up and see a bunch of notifications. A brief investigation revealed that Rasmussen Reports had Tweeted a screen cap of that day’s graph.
And then… Nate Silver retweeted the Rasmussen Tweet to throw a little shade. Nate has 3.2 million followers, so that explained all my notifications.
The funny part of the story is that I change my Twitter handle from time to time. Often it is a thinly veiled Cubs reference like Dr. Addison Sheffield or Dr. Eamus Catuli. Sometimes it is a reference to some bit of news that I found amusing like Dr. Humboldt Gator or Dr. Dark Matter Hurricane. Near the time of this incident Dr. Marijuana Pepsi, the real name of a woman who had just earned her PhD, was trending all over the internet so for some dumb ass reason I changed my handle to Dr. L.S.D. Snapple for a brief time.
So the one, and probably only, time Nate Silver will ever mention me plays out like this…
Rasmussen: “Our thanks to Dr. L.S.D. Snapple for his illustration…”
Nate Silver: “I’m not a polling expert like Dr. L.S.D. Snapple…”
The red line is for the immediate loading and unloading of passengers only …
My last crack at this -
My only assumption is that Silver’s model is run the the way Silver states it is run. True I cannot verify that he actually doesn’t do something completely different.
But testing that as a hypothesis I took eight of the highest rated polling houses, which by Silver’s description should be the biggest drivers of his tracker’s numbers, and looked at their movement over the past 4 to 6 weeks. On average they had a net drop of 4.5. Which supports the hypothesis that Silver is not lying about how his model works.
The hypothesis that Silver is not lying and that the highly rated houses are the bigger inputs is supported.
Now let’s test your hypothesis that Rasmussen’s movements are the significant factor in the 538 tracker’s movement over this past 4 to 6 weeks period.
By your graph over that period of time Rasmussen’s 14 day moving average dropped something like 3. Does not seem so different or big as to drive much when averaged with a bunch of others.
There’s over 20 polling houses going into the 538 algorithm.
For shits and giggles let’s imagine C+ rated Rasmussen was weighted as much as 50% as much those A+ to B+ ones (a likely over-estimate, but that is an unverifiable assumption), that C+ to B all gets the same (also a generous assumption), and that instead of the top tier showing that drop over that time period they had all, except for Rasmussen, been flat. And we’ll call it 20 going into the tracker. How much would the tracker had moved because of Rasmussen’s moving 3? 0.1%.
How about if it had moved 5 while everything else stayed flat. O.17% Nonzero but still not very “noticeable”. If it had moved 15?!? 0.5%. Can a pollster that has a lower weight probably move the model with a large enough swing? Not by a significant amount even with a very large swing.
How about we assume that Silver is lying and Rasmussen is not underweighted, everyone counts the same? A move of 5 while everyone else was flat would move the tracker by 0.25%, and a Rasmussen move of 15 would move the tracker all of 0.75%.
If your hypothesis or opinion is that the shifts you’ve seen in Rasmussen are responsible for significant moves of the 538 tracker then it is soundly falsified.
Hell let’s overweight Rasmussen! Instead of a lower weighted one of over 20 polling houses, instead of even equal weight as all the others of 20, we’ll credit it with being weighted twice as high, it is as if it was one tenth of the tracker all by itself. How much does it need to move to move the tracker by the 3 the tracker has moved if everyone else averages out flat? 30 points.
Maybe if you assume that Silver is lying and he actually counts every day’s result of Rasmussen as much as he counts ones that report every 3 weeks or less often. Then it and the other frequent reporters like Harris would dominate, even if they were lower weighted. Maybe. And I guess Silver not lying is unverifiable.
Nice Tweet-bot?
I am not assuming Silver is lying. That’s absurd.
Assume there are two pollsters, Q and R. Q is a A+ rated pollster that polls once a month and R is a C+ rated pollster that polls everyday.
Let’s say we have 2 data points from Q on day 1 and day 30 of some time period and both those data points are Trump -10. If we put those 2 data points, and only those 2 data points, into the 538 model my assumption is that it would return a flat line at Trump -10.
Furthermore say we have 30 data points from R and each data point for days 1 through 30 is Trump +0. If we put those 30 data points, and only those 30 data points, into the 538 model my assumption is that it would return a flat line at Trump +0.
Now let’s put all 32 data points into the model. My assumption is that at day 1 and at day 30 the model outputs something quite close to Trump -10 because Q is so much more highly rated than R. However, I’m not sure where exactly to excpect the model’s output to be on day 29. Even though Q is highly rated, it’s data is four weeks old at that point. My assumption is that the model puts very little weight on the four week old old data from Q and outputs something closer to R on day 29. Possibly something around Trump -2 or Trump -1. This assumption does not require Nate Silver to be lying.
What do you think the 538 model outputs on day 29 in this hypothetical DSeid?
In a hypothetical world in which there are only two pollsters going into the model, one A+ and one C+, then every rational analyst would keep the only A+ poll last report active and driving the numbers until it was replaced by that house’s new results. 538 is run by rational analysts.
On day 29 the model would output something quite close to Trump -10.
With only one quality pollster going into a model reporting only monthly any rational analyst would state that we have little ability to report on any interval change between those reporting dates. If a significant event occurred in the interim we would look to the C+ rated daily tracker to get some very tentative sense of directionality and magnitude of impact but its impact on the bottom line number output would still be minimal until the A+ one reported.
Of course with multiple high quality houses and more medium quality houses providing input to the aggregate, aging polls can get weights decreased as they age, with more recent quality house results having more strength and more frequently reporting houses with more like B and B- ratings getting pooled together, weighted appropriately lightly, but able to reflect shorter term changes. For 538 that means B rated YouGov contributes most to catching the most immediate changes. Rasmussen and HarrisX not so much. Ipsos a bit less immediate but still fairly frequent.
But I’ll play even more with your hypothetical. Let assume for the sake of discussion a less than completely rational analyst and in that world the A+ poll loses weight dramatically by day 29. What would be the output by 538’s methods? Still about -10. See the other thing that 538 does is shift for house effect and the C+ house, with its 10 point house effect, would have been shifted. Since it showed no change over those days it would move the output by zero. (Note same would be functionally the case if it was the A+ house with the house effect or they each had ones that contributed.) This helps make their output less volatile as different pollsters age out or drop new results.
PLEASE NOTE, and this was my main bit for this thread, their sophisticated methods do not completely remove all false signal volatility/noise resultant of the timing of new data inputs, the aging process, and MOEs or other error sources within each poll. I think it is as close to a gold standard as we can get but movements within that +/- 2 points that are not “real” may have to be expected even with the most sophisticated aggregation approach.
This is where our assumptions are different. It is entirely rational to weight fresh C+ data higher than four week old A+ data. It’s a C+ not an F-. I would be stunned if 538 did not have some sort of time decay for polls built into their model. A rational analyst strikes a balance between using the highest quality data and the freshest data.
There is exactly one University of Maryland/Washington Post poll in the 538 data set. They are rated A+ and the number in the weight column is 2.99 which is the highest weight in the whole data set. It was in the field Sept. 27-Oct. 5, 2017. My assumption is that this poll is given zero weight in calculating today’s data point. Your assumption is that that poll has been given the same weight for almost two years while they wait for another University of Maryland/Washington Post poll.
Frankly, your assumption is bonkers.
Good point about house effect, but I’d like to ignore it for the purpose of this hypothetical since it has no bearing on whether or not a big swing from a lower rated pollster can move the 538 needle. The hypothetical is not quite at that point yet, but that’s where this is heading.