tag:blogger.com,1999:blog-4624586630299165335.post1965990273847550693..comments2024-03-14T09:50:44.315+00:00Comments on Psychological comments: Steady as she goesAnonymoushttp://www.blogger.com/profile/09320614837348759094noreply@blogger.comBlogger9125tag:blogger.com,1999:blog-4624586630299165335.post-22622871223958906082015-03-11T23:52:31.596+00:002015-03-11T23:52:31.596+00:00I like brain studies. The problem being that there...I like brain studies. The problem being that there are too many of them, each having very low sample sizes. So, at some point, I stopped reading them. I prefer to read others peoples' reviews of those studies. It saves me the time to read them all. I appreciate you look at some of them.<br /><br />On IQ changes, there is a study that deserves to be cited more often, but that I rarely see (except in articles written by Nathan Brody and Arthur Jensen).<br /><br />Moffitt, T. E., Caspi, A., Harkness, A. R., & Silva, P. A. (1993). The Natural History of Change to Intellectual Performance: Who Changes? How Much? Is it Meaningful?. Journal of Child Psychology and Psychiatry, 34(4), 455-506.<br /><br />Here's the summary of Moffitt (1993) by Brody (2007) :<br /><br /><i>In principle, environmental variations associated with educational deprivations or educational interventions could result in cumulative changes in IQ. The data do not support this outcome. Rather, the results reviewed above suggest that relatively dramatic changes in the environment have vanishingly small influences on general intelligence in the long run, although they may have large short-term effects. These results, combined with evidence for stability of IQ, suggest that environmental variations commonly encountered do not have enduring influences on cognitive ability - g is a relatively resilient trait whose short-term perturbations are accompanied by a tendency for its phenotypic manifestations to revert to an enduring stable value, manifested initially in early childhood or infancy. This conclusion is buttressed by the results of a longitudinal analysis of changes in IQ reported by Moffitt, Caspi, Harkness, and Silva (1993), who administered the Wechsler Intelligence Scale for Children (WISC) test to a representative sample of children when they were age 7, 9, 11, and 13. They obtained test-retest correlations varying between .74 and .84, and concluded that for close to 90% of the children in their sample, variations in IQ over this period were small and attributable to random errors of measurement. They also found a subset of children who exhibited larger changes in IQ over this period. They identified 37 different environmental measures that might be related to changes in IQ, including socioeconomic status, changes in family composition, and such biological influences as impaired vision or perinatal problems. They found that this set of environmental variables was not associated with changes in IQ.</i><br /><br />In other words, it's difficult to understand what's causing IQ changes. The same thing applies to the Flynn effect.<br /><br />Brody, N. (2007). Heritability and the nomological network of g. In M. J. Roberts (Ed.), Integrating the mind: Domain general versus domain specific processes in higher cognition (pp. 427-448). Hove, UK: Psychology Press.Meng Hunoreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-54103340670245893522015-02-24T00:40:05.571+00:002015-02-24T00:40:05.571+00:00It's when I'm trying to edit a raw comment...It's when I'm trying to edit a raw comment, not in preview, that I get the difficulty.deariemenoreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-8374837453831769912015-02-23T18:27:58.415+00:002015-02-23T18:27:58.415+00:00Dear Andrew, Ouch. I admit I have generally fallen...Dear Andrew, Ouch. I admit I have generally fallen for the R2 argument, whilst at the same time knowing that if you show the data as frequencies in, say quintiles, then they are obviously very impressive, as Charles Murray did in the Bell Curve. I will look at all this again. I found one quote I liked, and copy it out here to check whether it was the one you had in mind: In fact, a validity coefficient of .40 has 40% of the practical value to an employer of a validity coefficient of 1.00 — perfect validity (Schmidt & Hunter, 1998; Schmidt, Hunter, McKenzie, & Muldrow, 1979).Anonymoushttps://www.blogger.com/profile/09320614837348759094noreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-17702464509303384462015-02-23T17:58:45.649+00:002015-02-23T17:58:45.649+00:00I agree that these would be very important additio...I agree that these would be very important additional variables. I suppose the authors could say that the brain changes they have revealed are the most important things to have measured. On you final point, I agree that measuring them a few years later would be salutary. Perhaps that is intended and is underway.<br />Anonymoushttps://www.blogger.com/profile/09320614837348759094noreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-46805090789465747252015-02-23T16:15:39.843+00:002015-02-23T16:15:39.843+00:00this "% of variation explained" business...this "% of variation explained" business came up in your blog. Men Hu wrote an excellent blogpost a while back on r-squared versus r on the statistic of interest, arguing that it is actually the latter and not the former that is of interest to the research worker, because the straightforward correlation coefficient maps in a linear and easily understandable manner to real-world effects, whereas the r-squared does not. It's well worth reading and includes a particularly good quote from Hunter and Schmidt http://humanvarieties.org/2014/03/31/what-does-it-mean-to-have-a-low-r-squared-a-warning-about-misleading-interpretation/ Andrew Sabiskyhttps://www.blogger.com/profile/13017718231961934541noreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-3124226220684938692015-02-23T14:02:29.246+00:002015-02-23T14:02:29.246+00:00I mean, "foundation" and "higher&qu...I mean, "foundation" and "higher" GCSE streams.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-34469110868230429102015-02-23T13:59:23.029+00:002015-02-23T13:59:23.029+00:00The study is interesting, but far from complete. A...The study is interesting, but far from complete. A larger study needs to be conducted in which the longitudinal gathering of IQ scores is accompanied by an investigation of what occurred in the lives of participants between their first and second tests, to discover what possible factors can be identified. Lots of things happen to children between the age of 14 and 17. Family break-up is known to have a big effect on adolescent's academic performance, motivation and mood. Some children start drinking and taking drugs at around that time. Illness is also a potential factor. Physiological tests should be conducted and a health history should be collected. Fourteen is also the age at which children are streamed into "foundation" and "gcse" streams, and choose subjects which may involve a lot of either mathematical reasoning, or verbal reasoning, or neither. Testosterone levels should be measured, as these are changing during adolescence, and have been observed to affect IQ. Another variable that should be measured is height. Perhaps those who experienced a rise or fall in IQ simultaneously experienced a rise in "height quotient" (i.e., they grew faster or slower than their age peers). This could point to relative lateness or earliness of adolescence as a factor. Intense study, or the lack of it, for a couple of years, in subjects where grades correlate with IQ scores, ought to have some effect on test performance, though findings in the literature indicate that these effects are likely to after a while. Therefore, to complete the study, there should be another follow-up a few years later, in which the participants are tested again to discover to what extent, if at all, the changes are stable. Again, potentially interesting factors and correlates should be looked at, such as whether and what sort of higher or further education, and what sort of career, has been pursued in the intervening time.<br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-1365969070477654142015-02-22T23:02:32.128+00:002015-02-22T23:02:32.128+00:00Sorry about that. I find that if you Preview, then...Sorry about that. I find that if you Preview, then there is a problem, but if you change it yourself and then press Publish it usually worksAnonymoushttps://www.blogger.com/profile/09320614837348759094noreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-36383743522822724482015-02-22T18:29:41.059+00:002015-02-22T18:29:41.059+00:00When I write a comment, and then try to edit it, y...When I write a comment, and then try to edit it, your software seems to misbehave. I am using the Safari browser on a Mac.deariemenoreply@blogger.com