CN reports on a study claiming that smarter people use iPhones (here’s the original white paper by chitika, a mobile ad network.) There are several different models used (linear, stepwise linear, and logistic) to predict iPhone usage share for a state. Population density and education level (percent with bachelor’s degree) turns out to have a positive coefficient; median income and median age have negative coefficients.
Yet within the US, iPhone use is correlated with income; check out mapbox’s maps. The areas where iPhones predominate (red on the map) are richer than those where Android phones predominate (green on the map). This is a textbook example of the ecological fallacy: rich states have Androids, rich people have iPhones. (Compare the political fact in the US that rich people vote Republican but rich states vote Democrat.) I’d be interested to see a better study of this.