Peer Influences - Effect Size d = 0.53 (Hattie's Rank = 41)
One meta-analysis is used:
Ide, et al (1980). Peer Influences. Evaluation in Education, 4, 111-112.
This is a very brief 1.5 page study. Many details are missing, so it is not possible to check the studies that were used. Overall, the average correlation size was 0.254. Correlations of peer influences with cognitive outcomes (grades or achievement test scores) averaged 0.194, while correlations with educational or occupational aspirations averaged 0.281.
Hattie used the average correlation r = 0.254 converted to d = 0.53.
However, one could argue that only the grade or achievement correlation of r = 0.194 should be used giving d = 0.40 lowering the ranking to 64th. Casting doubt on the ranking reliability.
Also, this illustrates the classic problem of comparing apples with oranges that arise in most of Hattie's synthesis. That is, other measures besides achievement are used to calculate effect sizes, in this case - students' aspirations.
Another issue is the researchers report a number of studies were NOT statistically significant, but it seems they used these studies to calculate averages. This is markedly different from Slavin (1990), who in his 'ability group' meta-analysis assigns d=0.00 to these. However, many other researchers argue statistically insignificant studies should not be used at all.
In any case, the authors caution,
'present findings should be considered preliminary' (p. 112).
Creativity - Effect Size d= 0.35 (Hattie's Rank=78)
One meta-analysis is used:
Kim, K. H. (2005) Can only intelligent people be creative? A meta-analysis Journal of Secondary Gifted Education, 16(2-3), 57-66.
Kim states the main purpose of this analysis is to
'conduct a quantitative synthesis of correlations between IQ and creativity test scores' (p. 58).Kim concludes,
'the negligible relationship between creatively and IQ scores indicates that even students with low IQ scores can be creative. Therefore, teachers should be aware of the characteristics of creative students - this will enable teachers to see the potential of each child' (p. 65).However, Hattie morphs the weak correlation coefficient r = 0.174 into an effect size d =0.35 and infers creativity influences achievement. The high effect size of d =0.35 is interpreted by Hattie to indicate a year's improvement in achievement!
This is clearly not what the study is measuring. Does IQ = achievement? Hattie infers that it does. So significant doubt is raised about the validity of this analysis in the context of VL - i.e., improving student achievement. The effect size, once again, is not calculated as indicated by Hattie in his chapter 2 - The Nature of Evidence.
So once again there is doubt about the reliability of the effect size, rankings, and interpretation.