I sometimes wonder how prevalent selection bias is in articles like this and the demographics they feature. If you're a magazine writer in NYC writing an artic

I sometimes wonder how prevalent selection bias is in articles like this and the demographics they feature. If you're a magazine writer in NYC writing an article like this, how do you find people who buy under the influence? Stop people on the street? Go to a crowded bar and chat people up? It seems likely that a decent percentage of your interviews are with friends and friends of friends. It also seems likely that many of those people would be in similar careers.