Are Democratic primary polls actually rigged against non-white voters?

Probably not, but people are still making dishonest arguments that they are

Last week, the Washington Post’s political science blog, the Monkey Cage, had an article by Matt Barreto, a professor at UCLA, that alleged that polls of the Democratic primary were “undersampling” black and Hispanic voters, decrease aggregate support for the candidates they liked and thus keeping non-white candidates off the debate stage. All respect t…