Linear regression test of funnel plot asymmetry

Test result: t = 0.84, df = 21, p-value = 0.4105
Bias estimate: 0.4455 (SE = 0.5305)

Details:
- multiplicative residual heterogeneity variance (tau^2 = 1.0108)
- predictor: standard error
- weight:    inverse variance
- reference: Egger et al. (1997), BMJ