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Luis A. Afonso
Posts:
4,758
From:
LIsbon (Portugal)
Registered:
2/16/05


Cohen d
Posted:
Nov 1, 2012 4:50 PM


Hodges g, Cohen d, GOOD FOR WHAT?
Karl L. Wuensch (2008) __This document is a guide for my students in Experimental Psychology . . . core.ecu.edu/psyc/wuenschk/docs2210/Strength_of_Effect.doc ____________
An example on significance difference between two groups: __Group 1 : N=6, Mean=22.67, St.dev.=4.274 __Group 2 :___8,______ 13.25,_______4.083
_______g = (22.6713.25)/4.15 = 9.42/4.15 = 2.27 very large effect following Hedges. ______________ Applying the standard NHST, with the current d, Student t, 6 + 8  2 = 12 degrees of freedom, one tail, 5% significance level, critical value= 1.782 _______T = (9.42  d)/ 4.15 = 1.782 _______d = 9.42  (1.782*4.15) = 2.02 And the difference on Population mean values is at least 2.02 with 95% confidence. Simply as this . . . better than CohenHodges procedure because provides a numeric alpha and uses the conventional NNHST (my acronym for nonull hypotheses statistical test . . .)
Luis A. Afonso[b][/b][i][/i][u][/u]
Message was edited by: Luis A. Afonso



