There's a part of me that wonders whether it's worth expending time and energy explaining just how shallow and uninformed Herman Cain is, since he is most assuredly not going to be the Republican nominee for president. But at the moment he's actually leading the polls, so I guess we have no choice. To wit, there is something he has said a few times in interviews that has bugged me, when he's asked about how the figures add up in his 9-9-9 tax plan. Here's an example:
Here is how we arrived at it. I had some of the best economists in this country help me to develop this plan. You know, my background is mathematics. It was a simple regression analysis. We took the government data and looked at how much tax revenue from personal income tax, how much tax revenue came from corporate tax, how much revenue came from capitol gains tax, how much revenue from the death tax. We added them all up and you do a simple regression analysis and say in order to reduce this much on corporate income, personal income and national sales tax, what should that number be if we equally break up those three buckets. It was a simple regression analysis.
I like how he says it was a "simple" regression analysis, when he knows full well that maybe 1 percent of reporters even know what regression analysis is. And guess what: That's the point. Herman Cain was a math major in college, so I would assume he knows what regression is and isn't used for. On the other hand, statistics and mathematics are not the same thing, so maybe he doesn't. But in order to figure out whether his plan adds up (spoiler alert: it doesn't), you would definitely not use regression. Regression is used to determine the relative influence of a group of independent variables on a dependent variable within a population. For example, you might want to know the relative influence of education, parent's income, and height on people's income. You could use regression for that (putting aside questions of causal direction). You can read more here if you care to.
But you wouldn't use it to figure out whether Cain's plan adds up. For that, you'd use something much simpler: algebra .09 times total corporate income, plus .09 times total personal income, plus .09 times sales = total tax revenue. CAP used this less obscure mathematical technique to determine that Cain's plan would generate only about half the revenues we need to run the government, all while increasing taxes for the poor and middle class and slashing them for the wealthy. Good stuff.
My guess is that Cain keeps saying that his plan was produced by a "regression analysis" when he's challenged because it's a way of saying, "It's based on a statistical technique that you don't understand that goes by a name you're unfamiliar with, so I just won the argument." And when he's dealing with reporters, he's usually right, about that at least.