Table 2 Synthesis of estimates
Study type | Number of estimates (K) | (a) Traditional synthesis | (b) Heterogeneity test and measures | (c) Unrestricted weighted least squares average (UWA) | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Fixed-effect model (z value)a | Random-effects model (z value) a | Cochrane Q test of homogeneity (p value)b | I2 statisticc | H2 statisticd | UWA of all estimates (t value)a,e | Number of the adequately powered estimatesf | WAAP (weighted average of the adequately powered estimates) (t value)a | Median S.E. of estimates (MSE) | Median statistical power (MSP) | ||
All studies (Hypothesis H1) | 1472 | − 0.092*** (− 354.98) | − 0.122*** (− 52.21) | 85,041.040*** (0.000) | 99.96 | 2833.7 | − 0.092 (− 46.69)*** | 1243 | − 0.092*** (− 42.90) | 0.019 | 0.998 |
Target region (Hypothesis H2) | |||||||||||
 Urban region | 919 | − 0.087*** (− 281.08) | − 0.114*** (− 43.43) | 40,279.710*** (0.000) | 99.93 | 1341.66 | − 0.086*** (− 42.45) | 757 | − 0.086*** (− 38.65) | 0.018 | 0.997 |
 Rural region | 135 | − 0.153*** (− 94.17) | − 0.174*** (− 18.31) | 3751.320*** (0.000) | 99.71 | 340.03 | − 0.153*** (− 17.80) | 126 | − 0.153*** (− 17.21) | 0.023 | 1.000 |
 Region unspecified | 418 | − 0.101*** (− 200.44) | − 0.124*** (− 26.02) | 38,976.320*** (0.000) | 99.82 | 563.87 | − 0.101*** (− 20.73) | 382 | − 0.101*** (− 19.80) | 0.018 | 1.000 |
Target corporate sector (Hypothesis H3) | |||||||||||
 Public sector | 24 | − 0.080*** (− 23.54) | − 0.090*** (− 10.62) | 103.050*** (0.000) | 71.86 | 2.55 | − 0.080*** (− 11.12) | 16 | − 0.078*** (− 10.18) | 0.020 | 0.976 |
 Private sector | 34 | − 0.128*** (− 27.51) | − 0.123*** (− 7.72) | 366.920*** (0.000) | 92.10 | 11.65 | − 0.128*** (− 8.25) | 21 | − 0.127*** (− 6.32) | 0.026 | 0.998 |
 Corporate sector unspecified | 1414 | − 0.092*** (− 353.23) | − 0.122*** (− 51.12) | 84,499.000*** (0.000) | 99.96 | 2815.63 | − 0.092*** (− 45.68) | 1207 | − 0.092*** (− 42.20) | 0.019 | 0.999 |
Target period (Hypothesis H4) | |||||||||||
 1990s or before | 315 | − 0.075*** (− 152.87) | − 0.105*** (− 25.70) | 14,735.520*** (0.000) | 99.80 | 490.18 | − 0.075*** (− 22.31) | 231 | − 0.074*** (− 19.40) | 0.018 | 0.989 |
 2000s | 689 | − 0.085*** (− 238.58) | − 0.111*** (− 37.60) | 31,563.520*** (0.000) | 99.95 | 1971.72 | − 0.085*** (− 35.23) | 535 | − 0.085*** (− 31.08) | 0.019 | 0.993 |
 2010s | 468 | − 0.138*** (− 230.70) | − 0.148*** (− 29.95) | 31,239.770*** (0.000) | 99.95 | 2081.65 | − 0.137*** (− 28.18) | 425 | − 0.138*** (− 26.86) | 0.019 | 1.000 |