{smcl}
{cmd:help sizefx}
{hline}
{title:Title}
{cmd:sizefx} -- Calculate Cohen's {it:d}, Hedges' {it:g}, and the effect size (ES) correlation ({it:r})
{title:Syntax}
{cmd:sizefx} {varlist} {ifin}
{title:Description}
{p}{cmd:sizefx} computes Cohen's {it:d}, Hedges' {it:g}, and effect size (ES) correlations ({it:r}) for the two variables specified in {helpb comments:varlist}. The two variables specified correspond to the variables in a {helpb comments:ttest}, although the "==" operator is not used in the {cmd:sizefx} syntax.
{p}The command displays Cohen's {it:d} statistic (Cohen 1988) using the pooled variance of the variables and Hedges' {it:g} statistic. The pooled variance for an unpaired t-test is used to calculate effect size even when using a dependent sample or correlated designs (Dunlap et al. 1996).
{p}Additionally, it displays the effect size (ES) correlation ({it:r}) using the value of Cohen's {it:d}.
{title:Examples}
. {cmd:sizefx} age1 age2
. {cmd:sizefx} before after
{title:References}
{phang}Cohen, J. (1988) {it:Statistical power analysis for the behavioral sciences, 2nd ed}. Hillsdale, NJ: Lawrence Earlbaum Associates.
{phang}Dunlap, William P., Cortina, Jose M., Vaslow, Joel B., and Burke,
Michael J. (1996) Meta-analysis of experiments with matched
groups or repeated measures designs. {it:Psychological Methods} 1
no. 2, 170-177.
{phang}Thalheimer, W., and Cook, S. (2002, August) {it:How to calculate effect sizes from published research articles: A simplified methodology}. Retrieved 01 Apr 2010 from http://work-learning.com/effect_sizes.htm.
Additional resources may be found at:
http://www.gseis.ucla.edu/courses/ed230a2/notes/effect.html
http://web.uccs.edu/lbecker/Psy590/es.htm
Links active as of 01 Apr 2010.
{title:Author}
Matthew S. Openshaw, The University of Texas at Dallas, USA
openshaw@utdallas.edu
{p}Please send comments, suggestions or constructive criticism to the above email address.
sizefx
v1.3
Update 01 Apr 2010