Table 1

Summary of standardized effect sizes for studies of individual sex ratio adjustment in various groups of birds and parasitic wasps.

Class of studyMean r95% CInstudiesX
All birds, studies independent0.252** 0.132–0.3841557
All birds, species independent0.261** 0.121–0.3911239
All birds, families independent0.252** 0.150–0.3699
All birds, studies independent 0.220** 0.116–0.3411474
All birds, species independent 0.217** 0.090–0.3501137
Mate, studies independent0.205* 0.088–0.3351145
Mate, species independent0.187* 0.041–0.34088
Help, species independent0.397* 0.191–0.56648
All wasps, studies independent0.319** 0.258–0.38365 1451
All wasps, species independent0.328** 0.262–0.39656 1206
Idiobionts, studies independent0.405** 0.318–0.49436 599
Idiobionts, species independent0.440** 0.353–0.54428 515
Koinobionts, studies independent0.217** 0.140–0.29629 182
Koinobionts, species independent0.219** 0.137–0.30528 173
  • * P < 0.01.

  • ** P < 0.001.

  • X is the fail-safe number, which is the number of unpublished studies averaging zero effect size that would have to exist for the overall mean effect size to be not significantly different from zero, calculated following (29); values in bold are robust, under the criterion that a fail-safe number is robust when X > 5n + 10.

  • Excluding the Seychelles warbler.