{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 "=" or "==" 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 unpaired t-test is used to calculate effect size even when using a dependent sample or correlated designs (Dunlap et al. 1996). {p}Additionally, effect size (ES) correlations ({it:r}) are displayed using both Cohen's {it:d} and Hedges' {it:g}. {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. Additional resources may be found at: http://www.gseis.ucla.edu/courses/ed230a2/notes/effect.html http://web.uccs.edu/lbecker/Psy590/es.htm http://work-learning.com/effect_sizes.htm Links active as of 24 Feb 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 v1.2 Update 24 Feb 2010