small impact on GPA. Comparing results across estimation techniques illustrates the consequences of ignoring the self-selection problem. When accounting for endogeneity using GMM and MLE, the predicted increase on GPA is close to 0.5. When ignoring the problem, the point estimate decreases to around 0.2. This suggests the students that choose to live on campus are more highly represented by students with lower incoming academic ability, i.e. students that can get the most bene t from living on campus. Ignoring the endogenous decision to live on campus results in these students bringing down the average performance of those living in the dorm, leading to a possibly incorrect conclusion that living in dorms has a relatively small impact on GPA. The results for Speci cation 2 in Table 2 largely mirror the results for Speci cation 1. Having ever lived on campus causes an increase in both semester GPA and cumulative GPA. Table 3 shows the results for Speci cation 3, the instantaneous e ects of living on campus. The instantaneous e ects are quite large. The instrumental variable methods GMM and MLE reveal that students that are currently living on campus are able to achieve a GPA that is between 0.7 to 1.0 higher due to living on campus. This may be due to increased utilization of academic resources provided on campus, positive peer in uences from other students living in dorms, or the organization, structure, and activities that dormitories provide their residents to encourage an environment conducive to learning. In an e ort to determine which estimation strategy is most appropriate we conduct Durbin-Wu-Hausman tests for endogeneity. The null hypothesis for this test is no endogene- ity, so failure to reject the null hypothesis may imply that a self-selection problem is not present, or it is accounted for by one or more of the control variables. Failure to reject the null hypothesis is not very conclusive, however, as it may be simply due to lack of statisti- cal evidence. Rejection of the null hypothesis implies that endogeneity is a problem, OLS results are inconsistent, and the instrumental variable strategies are more appropriate. To determine how well the controls can account for the choice to live on campus, the test is run under four cases: (1) with all controls included in the model, (2) with all controls except ACT/SAT test percentiles (TEST), (3) with all controls except parents income (PINC and PINC_d), and (4) with all controls excluding both ACT/SAT test percentiles and income. The p-values for the Durbin-Wu-Hausman tests are reported in Table 4. The rst column shows when using all controls, for all but one speci cation and estimation strategy choice, the exogeneity for DORM cannot be rejected. In Speci cation 1, when excluding TEST (whether only TEST [column 2], or both TEST and PINC [column 4]) exogeneity is strongly rejected. These results suggest a self-selection issue is certainly present, but using incoming ability as measured by ACT/SAT test scores as a control in the regression may account for much of the problem. The p-values for Speci cation 2 and 3 that use single semester GPA are often not statistically signi cant, indicating endogeneity may not be a problem in these speci cations.