Test for Unobserved Bias Using the Mantel-Haenszel Test Statistic
| Nonresident | Long-Inhabited | Recently Inhabited | ||||
|---|---|---|---|---|---|---|
| Γ | Pre | Post | Pre | Post | Pre | Post |
| 1 | 12.2 | 21.5 | 10.3 | 15.1 | 6.2 | 4.4 |
| 2 | 17.4 | 30.3 | 14.8 | 21.6 | 11.1 | 13.1 |
| 3 | 21.3 | 36.9 | 18.3 | 26.5 | 14.6 | 18.8 |
| 4 | 24.6 | 42.4 | 21.2 | 30.6 | 17.4 | 23.2 |
| 5 | 27.5 | 47.2 | 23.8 | 34.2 | 19.8 | 26.9 |
Note: Results were obtained using “mhbounds” in Stata Version 12 used for testing unobserved bias with binary dependent variables (see Becker and Caliendo 2007). Reported values are for the Mantel-Haenszel statistic Q + mh (assumption: overestimation of treatment effect). p-Values for all test statistics are less than 0.001 and thus are not displayed in the table. Pre indicates the prepolicy period from 1990 to 1996, post indicates the postpolicy period from 2000 to 2008. Γ is a measure of the degree of hidden bias required to change results of the estimated treatment effect from the kernel matching results (TABLE 5).