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brazil84 comments on Undiscriminating Skepticism - Less Wrong
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Say what? The gap is 35 points in 1973 and 27 points in 1990. How is this halving?
Aha, I misunderstood which chart you had in mind. I thought that your link was intended to go to the data for 17 year olds, but that you were unable to link it directly because the page used Javascript to flip between the charts for different ages. I see now I'm wrong about that - one can link directly to the chart for each age, and it sounds like you were pointing to the age 9 data.
So I'll try this again with the 9 year olds. I've taken the liberty of looking at the black-white gap graph instead of the scale score graph so I don't have to do any mental arithmetic to get the gap size at each testing. Looks to me like the gap consistently narrowed from 1973 to 1986, and has fluctuated from 1986 so it's sometimes wider, sometimes thinner, but no overall trend since then.
Regressing gap size on year like I did before gives a shrinking of .24 or .25 points per year. So the picture is more mixed than for the older kids: there's an overall shrinking, but it's only two-thirds what you get for 17 year olds, and the trend looks like it's stalled since the late 80s.
Still, I am not sure that this means Nisbett is wrong. Looking at the bit of Nisbett you quote yourself downthread, Nisbett does not seem to say anything about the math scores, which means looking at the math scores would not tell us whether Nisbett is wrong or right.
It is possible that Nisbett cherry-picked by ignoring the math data, but I think a .25 point per year narrowing is still evidence against that idea. At a quarter point per year, the math gap would disappear in about a century, which isn't much longer than the 75 years Nisbett suggests for science.
Of course there are ways to interpret the graph to argue that the gap is narrowing and on track to disappear, but if you look at it and use your common sense, it's just not a reasonable conclusion.
The reasonable conclusion - as you allude to -- is that the gap has been pretty much stable for a number of years.
You put more trust in your common sense than I do. I try to avoid depending exclusively on what my common sense infers from eyeballing noisy time series - that way lies 'global warming stopped in 1998'esque error.
I find your preferred interpretation reasonable, but I don't see why it would be unreasonable to look at the entire data and see a net narrowing. (Especially if we lacked the 2008 data, as Nisbett did.)
If the choice is between trusting your common sense and trusting someone with an agenda, I would say go with your common sense.
Here's a thought experiment: You show the graph I linked to to 10 statisticians, except you replace the labels with something less politically charged. For example, the price of winter wheat versus the price of summer wheat. And you ask them to interpret the graph as far as long term trends go. I'm pretty confident that 10 out of 10 would interpret the graph the same way I did.
Ditto for global surface temperatures. Take the temperature label off the graph and tell people it's the dollar to yen exchange rate. I bet 10 out of 10 statisticians will say the rate is basically flat for the last 10 years.
cupholder has the empirical data - which, you will note, is increasing in all cases - but do you really imagine that no-one's tried a blind test?
No I do not imagine so. But I'm a little confused. Are you saying that the absence of significant cooling is the same thing as the presence of significant warming?
PS: The empirical data is not "increasing in all cases." Indeed, by most accounts global surface temperatures have not met or exceeded the high reached 12 years ago.
Every 10-year trendline in cupholder's data was increasing.
If you give a statistician the 30-year or 130-year data set with the y-axis label taken off, they will tell you that there is no sign of a levelling-off.
A quick clarification: for each of the data links I posted there, the trendline is calculated based on all of the data that's shown, i.e. for the post-1998 data the trendline is based on the last twelve years, for the post-1970s data the trendline is based on all of the post-1970s data, and so on. In other words, only the data for the last 10 years of data really have a 10-year trendline.
[ETA: Unless you mean you calculated 10-year trendlines for each data set yourself, in which case feel free to disregard this.]
Here's a plot of the UAH index from 1998 to 2009.
http://www.woodfortrees.org/plot/uah/from:1998/to:2009/plot/uah/from:1998/to:2009/trend
The linear trend is definitely decreasing for this particular plot.
I'm seriously skeptical of this.
P.S. Are you saying that the absence of significant cooling is the same thing as the presence of significant warming?
Note that changing the beginning data point to either 1997 or 1999 makes the regression line have a positive slope. It's not at all surprising that there is enough variability that cherry-picking data is possible. Stuffing a positive outlier at the beginning will, of course, tend to do this.
Did you read the linked article?
[...]
1998 was a strong El Nino year - unusually high atmospheric temperatures that year in no way suggests that the earth has stopped heating.
I am far less confident.
I bet it would depend on exactly which data set you gave them. Do you give them data for the past 10 years, data since 1998, the data since they started measuring temperatures with satellites as well as thermometers, or the longest-running data set, which runs from 1850 onwards? If you just give them the last decade of data, they might well just write it off as flat and noisy, but if you let them judge the recent numbers in the context of the entire time series, they might recognize them as flat-looking fuzz obscuring an ongoing linear trend.
That sounds nice, but I don't know how practical that would turn out to be, in this case or in general. In this particular case, how can I even tell with certainty whether you have 'an agenda' or not? And what if the key participants in a debate all have some agenda? It's very possible that Nisbett has a 'politically correct' (not that I like the phrase, but I can't think of a better way of putting it) agenda, and that Rushton and Jensen have a 'politically incorrect' agenda. How do I know, and what do I do if they do? And so on.
How can you tell anything with certainty? The fact is that you can't. Respectfully, it seems to me you are playing the "I'm such a skeptic" game.
Let me ask you this: Do you seriously doubt that Nisbett has an agenda?
I would give them the data since the 1970s when sattelite measurement became possible.
Sorry. I was being sloppy in my earlier comment, and using 'certainty' as a shorthand for 'certainty enough for me to label you as Having An Agenda, and therefore to reject your interpretation of the data as Tainted With An Agenda.' It is of course true that you can't tell anything inductive with cast-iron 100% certainty, but what I'm getting at is the question of how to get to what you or I would practically treat as certainty (like if I put a 95% probability on someone Having An Agenda).
Let me rephrase: in this particular case, how can I even tell whether you have 'an agenda' with sufficient certainty to disregard whatever you say about the data, and retreat to my own common sense gut feeling?
Do I doubt he has an agenda in the sense that he believes he's right? A tiny bit, but only in the sense that I am never completely sure of another person's motivation for stating something.
Do I doubt he has an agenda in the sense that he wants to convince other people of what he believes? Not really.
Do I doubt he has an agenda in the sense that he has an emotional investment in the argument as well as rational considerations? Only a little...but then again, who doesn't get emotionally invested in arguments?
Do I doubt he has an agenda in the sense that he has political motivations for his article as well as self-centered emotional and rational ones? Quite a lot, actually. I don't think I could reliably tell Nisbett's emotional motivations apart from those that spring from his political agenda (whatever that is - Nisbett sounds like a leftist to me, but how the hell do I really know? There were rightists who crapped on The Bell Curve too.) Does it even make sense to distinguish the two? I'm not sure. (I suddenly feel that these are good questions to think about. Thank you for prodding me into thinking of them.)
Also, for whatever it's worth, I am just as sure that Rushton and Jensen have 'an agenda,' however you want to define that, as Nisbett does. Do I throw all their papers out and just go with my common sense?
To clarify, this doesn't mean I can't get behind the idea of being alert to other people's biases on some subject, but I'm not willing to push that to the point of a dichotomy between my common sense vs. someone with an agenda. Taking the global warming example, I'm sure many climate scientists have 'an agenda,' but I'd still tend to accept their consensus interpretation of the data than my own common sense where the two differ, and I think that's reasonable if I don't have time to dig through all of the research myself.
In that case I think I'm roughly 90% confident that fewer than '10 out of 10 statisticians will say the rate is basically flat for the last 10 years'. I am interpreting 'the rate is flat here' to mean that the net temperature trend is flat over time, as I believe we're talking about whether global warming is continuing and not whether global warming is accelerating. (Thought process here: I reckon a randomly selected statistician has at most a 4 in 5 chance of deciding that temperatures have been 'basically flat' for the last 10 years' based on the satellite data. Then the chance of 10 random statisticians all saying temperatures have been flat is 11%, so an 89% chance of at least one of them dissenting.)
By "having an agenda," I mean that Nisbett is emphasizing the facts that support a particular point of view and de-emphasizing the facts which undermine that point of view in order to persuade the reader.
So defined, one can ask whether Nisbett has an agenda. Do you have any doubt that Nisbett has an agenda?
So by your definition, the temperature trend is NOT basically flat between 1995 and the present, correct?
Not much. I think it is very likely that Nisbett suffers from confirmation bias about as much as everybody else.
Eyeballing it I'd say it's much more likely that temperatures rose since 1995 than that they stayed flat, so I'd say you're pretty much correct. I wouldn't dogmatically say it's not flat in big capital letters, but I think the rising temperature hypothesis is a lot more likely than the flat temperature hypothesis.
I'd double check my intuition by running a regression, but that'd stack the deck because of autocorrelation, and I can't remember from the top of my head how to fit a linear model that accounts for that.
You're looking at age 9, cupholder is looking at 17.
In that case he is looking at the wrong graph when he talks about "your random graph."
Yes, but in that case you aren't looking at the data that Nisbett referred to. As cupholder pointed out
Agree, but as I said to cupholder, it doesn't help Nisbett's argument if he is cherry-picking data.
But Nisbett is quoting from a study "which found improvement on almost all tests for African American 12th graders". That study may not even have contained the data on 9-year-olds. You can ask "Why didn't that study include that data?", well because they were comparing data for 12th graders.
Actually, it's not clear to me what study he is talking about. Here's what he says:
So I went to the NAEP web site and looked at the very first graph I saw. What study do you think he is referring to?
I take this to say that Hedges and Nowell examined lots of test results for African Amercicans 12th graders from 1965-1994. The test with the largest sample was the NAEP test. Since Hedges and Nowell were looking at 12th graders Nisbett is probably talking about the 17-year-olds.
I could be wrong. In any case, the trends have changed since 1994 so obviously the predictions don't hold.
This all seems pretty beside the point to me since the evidence that really matters is the adoption and skin tone studies. The other thing that becomes obvious is that there just isn't nearly enough data-- all the studies are decades old presumably because 1975 was the last time you could get grant money to study the issue. There certainly isn't enough to conclude, as you did, that there is obviously a genetic component.