T-Test Group Statistics age1 N Mean Std. Deviation Std. Error Mean Skill 25 or younger 4 20.75 2.217 1.109 26 or older 19 38.47 7.813 1.792 Independent Samples Test Levene's Test for Equality of Variances t-test for Equality of Means F Sig. t df Significance Mean Difference Std. Error Difference 95% Confidence Interval of the Difference One-Sided p Two-Sided p Lower Upper Skill Equal variances assumed 2.387 .137 -4.424 21 <.001 <.001 -17.724 4.006 -26.054 -9.393 Equal variances not assumed -8.410 18.319 <.001 <.001 -17.724 2.108 -22.146 -13.301 Independent Samples Effect Sizes Standardizera Point Estimate 95% Confidence Interval Lower Upper Skill Cohen's d 7.282 -2.434 -3.717 -1.111 Hedges' correction 7.555 -2.346 -3.582 -1.071 Glass's delta 7.813 -2.269 -3.552 -.942 a. The denominator used in estimating the effect sizes. Cohen's d uses the pooled standard deviation. Hedges' correction uses the pooled standard deviation, plus a correction factor. Glass's delta uses the sample standard deviation of the control (i.e., the second) group