metafor (version 1.9-2)

ranktest.rma: Carry Out a Rank Correlation Test for Funnel Plot Asymmetry for 'rma' Objects

Description

Rank correlation test for funnel plot asymmetry for objects of class "rma".

Usage

## S3 method for class 'rma':
ranktest(x, \dots)

Arguments

x

an object of class "rma".

...

other arguments.

Value

• An object of class "ranktest.rma". The object is a list containing the following components:
• tau
  the estimated value of Kendall's tau rank correlation coefficient
• pval
  the corresponding p-value for the test that the true tau is equal to zero
• The results are formated and printed with the print.ranktest.rma function.

Details

The function carries out the rank correlation test as described by Begg and Mazumdar (1994). The test can be used to examine whether the observed outcomes and the corresponding sampling variances are correlated. A high correlation would indicate that the funnel plot is asymmetric, which may be a result of publication bias.

References

Begg, C. B., & Mazumdar, M. (1994). Operating characteristics of a rank correlation test for publication bias. Biometrics, 50, 1088--1101. Viechtbauer, W. (2010). Conducting meta-analyses in R with the metafor package. Journal of Statistical Software, 36(3), 1--48. http://www.jstatsoft.org/v36/i03/.

See Also

ranktest, regtest

Examples

### load BCG vaccine data
data(dat.bcg)

### calculate log relative risks and corresponding sampling variances
dat <- escalc(measure="RR", ai=tpos, bi=tneg, ci=cpos, di=cneg, data=dat.bcg)

### random-effects model
res <- rma(yi, vi, data=dat, method="REML")

ranktest(res)