Bay Checkerspot Butterfly. Summaries of Observable Variables for Land Sales: Pre- and Postpolicy Levels Summaries (Means. Standard Deviations, and Counts) Calculated for Policy by Treatment Status by Period Groups
| (1) Group | (2) Period | (3) Price/Acre | (4) Acres | (5) Serpentine | (6) Slope | (7) Flood plain | (8) Observations | (9) Start | (10) End |
|---|---|---|---|---|---|---|---|---|---|
| Ctrl. | Pre | 20.52 [59.59] | 2.62 [14.04] | 0.03 [0.17] | 1.86 [0.97] | 0.15 [0.36] | 2,035 | 1988-01-04 | 2001-04-27 |
| Ctrl. | Post | 33.73 [73.61] | 1.89 [12.24] | 0.04 [0.20] | 1.85 [0.95] | 0.12 [0.32] | 1.353 | 2001-05-01 | 2007-12-28 |
| Trt. | Pre | 4.99 [6.32] | 8.10 [12.23] | 0.50 [0.52] | 2.48 [0.50] | 0.06 [0.25] | 16 | 1988-05-03 | 1999-07-02 |
| Trt. | Post | 13.80 [37.40] | 7.81 [9.91] | 0.79 [0.41] | 2.71 [0.37] | 0.03 [0.19] | 29 | 2001-05-29 | 2007-10-17 |
Note: Columns (3)–(7) contain the means (unbracketed) and standard deviations (square brackets) for each variable. Comparing Pre period means of control (Ctrl.) and treatment (Trt.) groups illustrates the prepolicy balance on these observable variables. The double-difference estimator essentially compares the Post-Pre difference for Trt. and Ctrl, but adds fixed effects. Price/acre denotes price ($100,000) per acre.