Linear regression test of funnel plot asymmetry

Test result: t = 0.06, df = 20, p-value = 0.9545
Bias estimate: 0.0711 (SE = 1.2321)

Details:
- multiplicative residual heterogeneity variance (tau^2 = 10.7461)
- predictor: standard error
- weight:    inverse variance
- reference: Egger et al. (1997), BMJ