Computing effect sizes

McShane and Bockenholt (2016) illustrate formulae and how to use G*Power to obtain sample sizes for comparisons of means (Cohen's d), correlations and proportions taking the variance of the difference into account.

You might find A guide to magnitudes of effect sizes and Calculating, Interpreting and Reporting Estimates of "Effect Size" useful. The following spreadsheet by Jamie DeCoster (2012) converts a single effect size, such as Cohen's d, to several others including Odds Ratios using references mentioned in the spreadsheet. There is also an effect size calculator and converter for individual statistical tests here. One could also convert a partial eta-squared to a Cohen's d by regarding the partial eta-squared as a squared correlation. It follows square rooting the partial eta-squared and entering it in Jamie's spreadsheet as a r will then allow you to read off the Cohen's d. Jamie has written other EXCEL spreadsheet calculators here. Howell (2013) p.627-8 gives formulae for conversions of effect sizes such as odds ratios and correlations to Cohen's d.

References

Baguley T (2012) Serious Stats. A guide to advanced statistics for the behavioral sciences. Palgrave MacMillan:New York. R code and formulae for a range of commonly used effect sizes are in Chapter 7 on pages 235-276.

DeCoster J (2012) Spreadsheet for converting effect size measures. Available from: http://www.stat-help.com/spreadsheets/Converting%20effect%20sizes%202012-06-19.xls (accessed 04.09.2014)

Field A (2005) Discovering statistics using SPSS Sage:London.

Howell DC (2013) Statistical methods for psychologists. 8th Edition. International Edition. Wadsworth:Belmont,CA.

McShane BB and Bockenholt U (2016) Planning sample sizes when effect sizes are uncertain: the power-calibrated effect size approach. Psychological Methods 21(1) 47-60. Available free as a pdf download via the psychnet website to CBUers.

Vacha-Haase T & Thompson B (2004) How to estimate and interpret various effect sizes. Journal of Counseling Psychology 51(4) 473-481. Details computing effect sizes in SPSS for methods including ANOVA and regression as well as showing conversion formulae expressing one effect size in terms of another.