So, where more racists are likely to live and express that online, you're more likely to run into a racist? Shocking, I tell you.
Please re-do the study in places where casual racism isn't tolerated and is a (real-life) arrestable offence... people moan and whine about the police "wasting their time nicking someone for saying something offensive", but I bet that it results in a lot less racist acts of more serious natures.