Does having attended college influence the effect of being exposed to 'outsiders' on exclusionary attitudes? Another way to ask the same question is this: is there evidence of a differential impact of treatment, conditional on attending college versus not attending college? Calculate the necessary quantities to answer this question and interpret the results. Consider the average treatment effect for those who attended college and then those who did not.

As the numbers or data necessary to answer this question are not included, we are not able to make calculations based on this question. However, we are still able to think of the question and develop a theory about the answers without the need for calculations.

People who have "exclusionary attitudes" are usually those who are not accepting of people with different ideas or values, or people who are different from themselves (ethnicity, gender, etc.). Such people are generally not accepting of strangers, and have a hard time opening up their social circle.

It is very likely that attending college and being exposed to "outsiders" has an impact on such exclusionary attitudes. It is likely that people who are exposed to "outsiders" are more likely to become accostumed to them, and thus feel less threatened by their presence. This people are also more likely to eventually accept such "outsiders" as members of their circle.