January 9, 2010

Spot temperature:Climate::Test score:____________

I fully expect that within a week (if not yet already) some climate-change skeptic will use the cold wave currently freezing much of the country as an argument that climate changing really isn't happening. And every time there's a vicious cold snap in winter or a cooler-than-average summer we get the argument. And some reporter and editor decides to devote part of the ever-shrinking news hole to bad coverage of the issue, while a relative handful of reporters use the question as an opportunity to educate readers about the difference between weather and climate.

Today, I'm sitting in central Florida with more layers on than I usually need in early January. It's colder weather than usual. But we're in a warming climate, because in the long run of decades (or centuries) the current cold wave is just noise, and the trend is towards a warmer atmosphere. "Just noise," you may be thinking through chattering teeth, "tell my heating bill that it's just noise." The current cold wave is nasty for individuals today (and a few days more), but it's temporary.

The variability of weather makes sense to most people because we have enough experience to distinguish between spot temperatures and broader patterns. We know that temperatures have daily and seasonal cycles. But the cyclical nature of weather does not give us enough background to grasp climate change. For that, you need data. A lot of data. A lot of data from a lot of places and times, of different sorts, with a number of experts sifting through it.

And even then you get climate-change conspiracy theorists, including someone who's evidently a hacker.

You can probably guess the logical analogue here: we do not have anywhere near the same density of data on student achievement that we have on climate, and yet we draw bold conclusions about the underlying achievement from a relative paucity of noisy data. As I wrote in August, we need to learn how to make decisions with noisy data. But in terms of broad trends in achievement, it is a bad habit of Americans to equate the latest test scores with long trends. 

And that doesn't even touch the question of whether test scores are like temperature readings. Ah, but they are, if you're talking about your and my outside thermometers: placed at different heights, in different conditions (sheltered, out in the open, shade v. sun), different ages of the thermometers (and thus consistency of the readings across the years). I am sure that background thermometers in these varied conditions are highly correlated in the sense that when it's colder, they're all colder, and when it's warmer, they're all warmer, and so the correlations across time are likely to be very high. But I wouldn't use them in any scientific research.

Stay warm, and have whatever hot beverage you like!

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Posted in Education policy on January 9, 2010 10:45 AM |