Linear regression test of funnel plot asymmetry

Test result: t = 0.46, df = 29, p-value = 0.6522
Bias estimate: 0.3003 (SE = 0.6595)

Details:
- multiplicative residual heterogeneity variance (tau^2 = 1.1738)
- predictor: standard error
- weight:    inverse variance
- reference: Egger et al. (1997), BMJ