Re: First Solid Evidence that the Study of Music Promotes Intellectual Development

[Christopher D. Green]

Ronald C. Blue wrote: http://www.psychologicalscience.org/media/releases/2004/pr040819.cfm First Solid Evidence that the Study of Music Promotes Intellectual Development There is some fairly tricky use of statistics in this study (which I think I would have questioned had I been a reviewer). See the table below (copied from the aticle). Note that the raw IQ increases (over 36 weeks) were 6.1 for keyboard, 7.4 for voice, 5.2 for drama and 3.9 for no lessons. TABLE 1 Mean Sample Characteristics of the Four Groups of Children Sample characteristic Group                      Keyboard     Voice       Drama       No lessons n before lessons        36          36          36            36 n after lessons         30          32          34            36 Age (days over 6 years) 74 (78)    102 (78)     75 (85)      113 (80) Family income          4.6 (1.3)   4.3 (1.4)    4.3 (1.4)    4.1 (1.4) Full-scale IQ         102.6 (8.8)  103.8 (10.9) 102.6 (13.6) 99.4 (9.7) before lessons Full-scale IQ         108.7 (12.5) 111.4 (12.6) 107.7 (13.8) 103.3 (9.9) after lessons ------------- Note. Standard deviations are in parentheses. Age is listed as days over 6 years on September 1 (before lessons). Family income was measured in increments of $25,000 (15less than $25,000; 25$25,000–$49,999; 35$50,000–$74,999; and so on). There was no difference among groups in age, family income, or full-scale IQ when the children were tested initially (before lessons). The difference among groups in full-scale IQ after the lessons was reliable (p5.05). ------------- Fig. 1. Mean increase in full-scale IQ (Wechsler Intelligence Scale for Children–Third Edition) for each group of 6-year-olds who completed the study. The analysis then proceeds as follows: "The two music groups had increases of similar magnitude despite differences in teaching style (p>.8). The two control groups also had similar increases (p>.7), which indicates that drama instruction is not an extracurricular activity associated with notable increases in intellectual development.    "Similarities between the two music groups and the two control groups justified collapsing the data across groups in order to maximize power in tests of the central hypothesis. Compared with the control groups, the music groups had reliably larger increases in full-scale IQ, t(130)51.99, p < .05." First off, I do not understand what the p-values in the first sentence refer to -- "magnitudes" are not typically given as probabilities. Whatever they are, I'm not convinced that the "difference" of .8 and .7 "indicates" anything as definitively as the authors suggest, nor that it justifies grouping the different conditions in this (and only this) way. Note that the raw differences in IQ increases between keyboard and drama were LESS than those between keyboard and voice (so, why not, e.g.,  group keyboard and drama together, in which case the conclusion would be that voice lessons increase IQ, but not keyboard or drama?). Second, although it is said the conditions were grouped in order to "maximize power," it seems likely (to me, anyway) that they were grouped this way primarily because the obvious (and unreported) 1-way ANOVA that  would have normally have been applied to this data came up non-significant and so another aproach had to be developed ad hoc. Now none of this is out and out "wrong," it's just all a little "stretched" and, in any case, hardly justifies the "incontrovertable" label that APS gives the results in its PR blurb. I remain skeptical. Regards, -- Christopher D. Green Department of Psychology York University Toronto, Ontario, Canada M3J 1P3 e-mail: [EMAIL PROTECTED] phone: 416-736-5115 ext. 66164 fax: 416-736-5814 http://www.yorku.ca/christo/ ============================ . --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]