The Abecedarian project and other flawed studies

I’ve decided to give up blogging on IQ. But, I can’t resist:

Hambrick, 2012. IQ Points for Sale, Cheap. NYT.

We shouldn’t be surprised if extraordinary claims of quick gains in intelligence turn out to be wrong. Most extraordinary claims are. But we shouldn’t be totally discouraged, either. Results of studies like the Abecedarian project suggest that intelligence can be increased by making improvements in people’s environments, and that this can improve people’s lives.

But such studies also suggest that meaningful increases are not likely without a substantial commitment of resources. If we lose sight of this fact, this is a commitment we may never make.

Here was Baumeister and Bacharach’s discussion of the Abecedarian project:

Notwithstanding all the exorbitant praise from culturists, there are numerous and profound problems with the Abecedarian Project as Spitz (1986, 1992, 1993b, 1999) has trenchantly detailed. Farran (in press) also counseled “some caution” in interpretation of results from publications describing results of the Abecedarian Project. For instance, rather than report in gmeans and standard deviations on assessment measures, graphical data are often presented”… in figures which have a tendency to inflate group differences.” We think of this ingenious technique of data analysis as “the ordinate stretch effect-size calculation.” In addition to some artful analysis procedures, numbers of children assessed vary acrossdifferent measures making it difficult to determine group means. Numbers of subjects reported also varies across publications. Again, Farran states: “At a minimum some explanation of thedifferences would be helpful. These variations can lead to an impression of the manipulation[italics added] of readers rather than straightforward reporting …” Analytical incongruities notwithstanding, a major unexpected problem is that the control childrendid not behave according to the plan in that their mean IQ did not fall within the range of mental retardation (a five-point IQ difference at 12 years, 94 vs. 89). Spitz (1999, p. 282) recently observed that this is hardly a “… propitious outcome as far as the Project was concerned,because the Project’s purpose was to prevent mental retardation…. ” The Milwaukee Project, forall its problems, was at least conceived on the basis of a far better risk indicator for mental retardation: low maternal IQ. At age 15, the 4.6 point WISC-R IQ difference in the Abecedarian Project was not statistically significant (Farran, in press). The mean ability test score of the intervention group wassomewhat higher than the control group’s at 6 months, shortly after they entered the Project. Although their score remained in the average range throughout, by 18 months, it was appreciably higher than the control group’s only because the mean score of the control grouphad declined until it began, by 48 months, a steady recovery. In general, the experimental group never increased in IQ, but remained in the average range. Nor did the control group decline intomental retardation. The final IQ difference, not incidentally, was about the same as thedifference at 6 months; a difference that Ramey, Yeates, and Short (1984) admit cannot be attributed to the intervention.

In regard to this conspicuous lack of enduring effect in the Abecedarian Project, Spitz (1999, p.283) raised a question and then proceeded to answer it: “What happened during those first 1.6months at the day care centre to produce an effect worth 6 points, whereas an additional 4 1/2years of massive intervention ended with virtually no effect? It seems to me that it is not unreasonable to infer that nothing happened, but rather, some initial difference in the control and intervention groups had (by chance) escaped randomisation, and revealed itself at sixmonths of age.” We found similar problems with the IHDP. After a scrupulous, detailed, and even-handed reevaluation of both the Abecedarian and IHDPprojects Bruer (1999, p. 172) also concluded they “… hardly support a claim that early interventions have substantial, long-lasting, and positive effects on lifelong intelligence and school achievement.” He goes on to add: “One of the greatest abuses to the cause of children ismisrepresenting the effects of early-intervention programs” (p. 173). (Early Generic Educational Intervention Has No Enduring Effect on Intelligence and Does Not Prevent Mental Retardation: The Infant Health and Development Program)

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One Response to The Abecedarian project and other flawed studies

  1. B.B. says:

    I’ve decided to give up blogging on IQ.

    Thats a shame.

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