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.
God plays dice 
This is just a minor nitpick, but I’d say “voted” instead of “vote” in that last paragraph: Andrew Gelman (author of the book) has revisited the rich states vs. rich people when it comes to voting, and the results don’t seem to hold up in the 2012 election
http://scholar.harvard.edu/feller/publications/red-stateblue-state-divisions-2012-election