Monday, November 26, 2007

This is another DD (dissertation dish - technically this one is a thesis dish for a specialist degree)

This thesis was completed by Carrie Adkins (2006 - click here to find complete reference citation). The title of this thesis was "The The Correlation between Wechsler Adult Intelligence Scale III and Woodcock-Johnson III Cognitive Abilities and WJ III Achievement for College Students: Which is a better predictor of reading achievement?"

  • The present study is intended to examine whether the Wechsler Adult Intelligence Scale III or Woodcock-Johnson III Cognitive Abilities would better predict reading achievement on the WJ III Achievement in the college student population. Participants included 29 college students attending a university in the Midwest, being evaluated for a learning disability or academic accommodations. Data were analyzed using Pearson r correlation, Fisher z, and t-test for each intelligence test in comparison to achievement subtests. Results from this study indicated that both IQ scores obtained from the WAISIII and the WJ-III COG correlated with reading significantly, but not highly enough to be construed as achievement tests due to only moderate correlations. Considering the results of this study an examiner may choose either instrument to use when assessing intelligence. Limitations to this study are presented.
Brief blogmaster comments:
  • The thesis author appropriately points out the significant limitation in terms of small sample size and the need for replication in larger samples.
  • The WAIS-III FS IQ correlated .56, .66, and .24 with the WJ III Ach. tests of Letter-Word Identification, Passage Comprehension, and Reading Fluency. The WJ III GIA correlations with the same reading measures were .62, .65, and .34. Statistical tests revealed no significant differences between the respective WAIS-III and WJ III cognitive-reading correlations.
  • A limitation that should be noted is the significant restriction of range of talent/ability. The WAIS III FS IQ had an SD of 14.7 (almost normal), while the WJ III GIA SD was 10.1. The SD's for the respective WJ III achievement tests ranged from 9.8 to 11.7. Clearly there was significant restriction of range on the WJ III measures (due to the referral nature of the sample), a finding that suggests that the WJ III cognitive/achievement correlations are under-estimates of the population correlations. It would have been nice if the author would have presented "corrected" correlations (for range restriciton). Most likely the WJ III GIA correlations with achievement would have been higher.
  • Finally, I would like to have seen the correlations between the respective WAIS-III composite and WJ III CHC composite/cluster scores and reading achievement. Unfortunately, these are not reported.
Conflict of interest note - I'm a coauthor of the WJ III

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