The sample was from a subset (geolocated tweets) and involved only a very specific set of keywords. In other words, this was not an exercise to see how many rac

The sample was from a subset (geolocated tweets) and involved only a very specific set of keywords. In other words, this was not an exercise to see how many racist tweets there are. It was an exercise to see where the racist tweets generally come from. All that was needed here was a relatively small random sample. So the analysis, at least in terms of the sample size itself, is almost certainly valid. You may have misunderstood the point of the post...