— Rick Wilson (@TheRickWilson) April 27, 2016
If you can’t see the tweet, and tweets are ephemeral, the screen shot is also given. Now I do not give a damn about the election, so please not one word about it. The point I want to make has nothing whatsoever to do with Trump, Cruz, Hillary, anybody.
This bald fellow Wilson posted the graph which you see. The legend says (in red) “Unfavorable” and (in dark grey) “Favorable”. Wilson wrote “Trump just said his unfavs have gone down. False.”
Is Wilson right? Of course not.
But why might Wilson have thought he was? Because of The Deadly Sin Of Reification, which has claimed another victim.
Look at the data! The “unfavs” had indeed gone down, just like (presumably) Trump claimed. They were up one survey period before, and they went down in the last one. Up, then down. Therefore down. What could be clearer than that?
I also do not give a fig about the survey results. All surveys are “scientific”, anyway, despite the claims you have heard. It does not matter to us, here at least, where the numbers came from, how they were measured, or their uncertainty, which must be at least non-zero and is probably healthy, nor do I care what the terms mean (just what is “unfavorable”?). To us, as to Wilson, the data is the data.
See that red line (and grey line)? You’re not alone. That’s all, or mostly all, people do see. The data disappears in the presence of this mesmerizing fiction. The model becomes more important than reality. Reality is tossed overboard and the line cherished. The data are boring, dry observations. The model is scientific! The Sin is gnosticism, where “what is really going on” is the true reality, not reality itself.
Wilson was so enraptured by the line that he failed to see what was before him.
“But Briggs, there’s a trend in the data. That’s what Wilson meant.”
No, it isn’t. Mistaking the “trend” for what actually happened is the Deadly Sin. This Sin is ubiquitous. It’s so common that it’s positively rare to see a graph (or its interpretation) that doesn’t fall prey to it. Look at any of your favorite global warming sites for examples (skeptic or lunatic); almost anywhere there is a “time series” you will see the Sin. Graphs without the Sin are as common as reactionaries in History Departments.
I joined Statistics / To see the Sights / And what did I see? / I saw the Sin.
We have talked about trends until my knuckles bled. There is no trend in the data; there is never a trend in any data. Something, actually, many, many, countlessly many things, caused each survey point to take the value it did. The cause is in the people answering the question. Events which were noticed by the people and which led them to give the answers they did are in the world, and in other people.
But there is no trend “in” the data. The data are just measurements. What we’re really interested in, in this or any time series graph, is what caused the measurements. In sociological graphs, everybody will pretend they know (of course, it is not impossible that some soul might know) what caused the measurements. In physical graphs, usually many physical forces will cause the measurements; and with physics, we sometimes have a reasonable chance to discover these causes.
Probability & Statistics is useful for only one thing: to quantify the uncertainty in propositions we cannot induce or deduce. “The value of Trump’s unfavorable in the next survey will be 60%” and the like can be given a probability conditional on certain evidence and assumptions (the probability will change with different evidence or different assumptions). That’s it. In cases like this, that model (red line) might, or might not, be useful.
Probability cannot tell us what caused the measurements. This is why the red line is useless, and even harmful, absent predictions. This is why hypothesis testing (using p-values or Bayes factors) should never be used, because they fool you into thinking you’ve understood cause. But if we knew the causes, we don’t need probability!
I have tried explaining the Deadly Sin of Reification many times. The more formal math or statistics education a person has, or the more they’ve seen modern graphs, the more difficult it is for them to comprehend the Sin. I get nothing but blank stares, usually. Professors are especially suspicious. They’re hesitant to dismiss the data, but they’re sure their models mean something.