Difference-in-Difference Matching Results: Average Treatment Effects on the Treated (ATT) for Columbia County with Sample Limited by Acreage
| Outcome: Change in Land Cover Proportion, 2001–2012 | Treatment: Transactions from Farmers to Nonresidents | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Regression Adjustment with Radius Matched Sample (n=3, r=0.01) | Regression Adjustment with Radius Matched Sample (n=5, r=0.01) | Regression Adjustment with Radius Matched Sample (n=6, r=0.01) | |||||||
| ≤ (acres)a | ∞ | 90 | 70 | ∞ | 90 | 70 | ∞ | 90 | 70 |
| ATT on Agb change | −0.1208** | −0.1523* | −0.1530* | −0.1132** | −0.1482* | −0.1250 | −0.1168** | −0.1371* | −0.1284 |
| (0.0578) | (0.0858) | (0.0832) | (0.0570) | (0.0846) | (0.0845) | 0(0.0569) | (0.0858) | (0.0850) | |
| ATT on hay change | 0.1293** | 0.1431 | 0.1032 | 0.1139* | 0.1377 | 0.0786 | 0.1124* | 0.1378 | 0.0843 |
| (0.0620) | (0.0894) | (0.0942) | (0.0609) | (0.0894) | (0.0889) | (0.0606) | (0.0911) | (0.0906) | |
| ATT on mismatch change | 0.0837 | 0.0568 | 0.0514 | 0.0709 | 0.0581 | 0.0282 | 0.0716 | 0.0591 | 0.0341 |
| (0.0529) | (0.0822) | (0.0816) | (0.0533) | (0.0802) | (0.0775) | (0.0531) | 0 (0.0817) | (0.0793) | |
| PS-test (B/R) | 41.0/0.91 | 43.6/0.38 | 46.7/1.04 | 27.5/1.13 | 39.8/0.51 | 34.0/0.92 | 23.8/1.00 | 43.2/0.51 | 40.3/0.47 |
| N treated: on support (all) | 46 (49) | 28 (32) | 29 (32) | 46 (49) | 28 (32) | 29 (32) | 46 (49) | 28 (32) | 29 (32) |
| N control: matched (all) | 104 (609) | 67 (401) | 64 (345) | 155 (609) | 102 (401) | 98 (345) | 179 (609) | 115 (401) | 114 (345) |
| N total | 150 (658) | 95 (433) | 93 (377) | 201 (658) | 130 (433) | 127 (377) | 225 (658) | 143 (433) | 143 (377) |
Note: Treatment: transactions from farmer to nonresident happen between 2002 and 2010; control = farmer owner throughout the whole period. Robust standard errors are in parentheses.
↵a Extra-large agricultural parcels are less likely to be recreational second homes, so we can see estimation with large parcels (> 90 acres) tend to give smaller ATTs. When we further restrict the sample to 70 acres (29 treated), the increasing variances dominate the changes.
↵b Ag denotes agricultural land cover, except hay.
↵* p < 0.1;
↵** p < 0.05;
*** p < 0.01.