Persuasion Tactics with Numbers
28th February 2010
Consider this Figure from the IPCC (through the Wall Street Journal), the UN climate change panel that is driving the international conversation on policy. If a problem can be fairly expressed in one Figure, this is it.
All you see are the colored lines in the middle of the Figure that meander like Old Man River until 1900 when they take off like a rifle shot with a couple of ricochets in 1950 and 1995, but then return to a trajectory that looks like escape velocity from Planet Earth.
Houston, we’ve got a problem!
A persuasive problem. Those colored lines draw your eyeball, your attention, and your evaluation. Zig-zag, zig-zag for thousands of years, then the rocket shot. Just follow the colored lines . . . like Homer Simpson.
Now, let’s turn up the light a bit and make that gray background more noticeable. Didn’t really see it, did you? Of course not. It’s designed to read like Background when it is actually Foreground. That dull, plain, and unimportant gray contains the most important Numbers in this Figure, but the IPCC hid that from you to Simplify the data.
Notice two important perceptual qualities about the gray mass. First notice how wide it is, especially compared to the range of the zig-zagging lines. The lines essentially are the mid point of Old Man River while the gray background is the banks of the river. Thus, the Old Man River of global temperature is wide and wanders mightily.
But, second, now note how no colored line at any time ever jumps the banks of the river’s width anywhere. In scientific terms this means that the wandering of the lines across all points and all times is within the Random Variation or the banks of Old Man River; the lines never jump the banks of Old Man River and that means there is no scientific evidence of any temperature change in the last one thousand years this Figure displays.
Any one trained in statistics can see the mean variation of the colored lines never exceeds the 95% confidence band of the gray background. Unless one chooses to be Fooled by Randomness and find meaning in the tea leaves, the best scientific data we have shows all that zig-zagging is just the normal variation of Old Man River.
And the IPCC hid that fact in plain sight which is always most persuasive. Make the Favorable Argument Obvious and make the unFavorable Argument Obscure.
I’ll give the IPCC credit as persuaders. They understand the Rule: All Bad Persuasion Is Sincere. There is an obvious lack of sincerity when you persuade with statistics like this. However, since the IPCC bills itself as a scientific unit, I’d have to caution them on another rule: All Insincere Science Is Bad.
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