There is no "bigotry" there... It is an objective fact that (especially in the US) lower socioeconomic status is higher correlated with worse health outcomes. T

There is no "bigotry" there... It is an objective fact that (especially in the US) lower socioeconomic status is higher correlated with worse health outcomes. The author is pointing out one of the possible methodological flaws in studies evaluating the health impact of standing while working (i.e. by selecting for folks who stand at work, they are _also_ selecting for people of lower socioeconomic status, and it's likely the socioeconomic factors outweigh the sitting/standing distinction in terms of health).