Topics: Economics and Personal Finances, Socioeconomic Class. 1  Richard Fry is a senior researcher focusing on economics and education at Pew Research Center. 2  Rakesh Kochhar is an associate director of research at Pew Research Center.
In the United States, the Census Bureau determines who is poor using an economic poverty measure, by calculating official poverty estimates using a set of dollar-value thresholds, or minimum amount of income needed to meet basic needs, that vary by family size and composition.
However, people with smooth brains or lissencaphaly tend to get the lowest IQ's, which is around 20. Adaptive behavior ratings scales can go lower, but there's really no point, because once you get to IQ's that low, there's virtually no real difference in performance.