How Not to Be Wrong: The Power of Mathematical Thinking

by Jordan Ellenberg

This is a perfect example of the soup you get into when you start reporting percentages of numbers, like net job gains, that might be either positive or negative. Wisconsin added ninety-five hundred jobs, which is good; but neighboring Minnesota, under Democratic governor Mark Dayton, added more than thirteen thousand in the same month. Texas, California, Michigan, and Massachusetts also outpaced Wisconsin’s job gains. Wisconsin had a good month, that’s true—but it didn’t contribute as many jobs as the rest of the country put together, as the Republican messaging suggested. In fact, what was going on is that job losses in other states almost exactly balanced out the jobs created in places like Wisconsin, Massachusetts, and Texas. That’s how Wisconsin’s governor could claim his state accounted for half the nation’s job growth, and Minnesota’s governor, if he’d cared to, could have said that his own state was responsible for 70% of it, and they could both, in this technically correct but fundamentally misleading way, be right.