You have this from that Vaush google doc, don't you? Here is a good response to it:

https://docs.google.com/document/d/1bT_Q3TXZX0ZjnNS_QMsR-MEPut7S5EIkFeAkIO7vEGI/edit

For instance, for the "enormous meta analysis":

“First, many of these studies measured ethnic diversity in a way that would call a half White half Black neighborhood and a half British American half German American neighborhood equally diverse. More specifically, ethnic diversity was often measured as the probability that two randomly selected two people from the same region would be of different ethnics groups were the list of possible ethnic groups included not 3-6 “races” but, rather, 100+ ethnic groups. Thus, many of these studies looked at ethnic, rather than racial, diversity. This is problematic because ethnic groups are far more genetically (and phenotypically) similar than races are.

The second problem with this meta-analysis is that many of the studies referenced controlled for the mechanisms by which ethnic diversity might damage social cohesion. For instance, many studies controlled for income inequality and crime. The results of such an analysis will be misleading because ethnic diversity might cause a decrease in social cohesion by causing an increase in crime and income inequality. Thus, many of these studies controlled for the effects of diversity and then concluded that diversity had not effect.

The worst of these are studies that actually controlled for racial diversity. For instance, Aizlewood and Pendakur (2005) and Andersen and Millligan (2011) both found that the proportion of a neighborhood which is non white negatively correlated with its level of social cohesion but that ethnic diversity had no, or a positive, impact on social cohesion, after controlling for the effects of variation in the size of the population that isn’t white! Several of these studies were counted as “failed replications” by Meet and Tolsma.”

The study of 200 students found the exact opposite of what Vaush is claiming:

Second, we find that subjects who are paired with a partner of a different race or nationality send back less money to their partner. Eleven out of the twelve times in which the recipient sent back nothing, the sender and the recipient were of different races. These effects are stronger than the social network effects and survive controls for the social connection of the sender and recipient. This finding is also unsurprising, but serves as a reminder of the continuing barriers that racial and national differences may create” (p.814)

and others:

Tatu Vanhanen analyzed 176 countries in the period from 2003-2011. He found that Ethnic diversity has 0.812 correlation with ethnic conflict. Meaning that more diverse countries tend to have more violent conflicts.