Tag: IQ

Raven’s Advanced Progressive Matrices item taxonomies

There are classifications galore.  Below is a comparison of one by DeShon, Chan, and Weissbein (1995) with one by Styles (2008):

DeShon et al
Styles ? Analytic Both Either Visual
? 1 0 0 0 0
D/T 0 1 0 0 0
Distribution 0 2 0 0 0
Equation 0 1 3 0 8
S/D 0 1 0 0 0
S/D/T 0 3 1 0 0
S/T 0 0 0 0 1
Seriation 0 1 2 4 3
Transformation 0 3 0 0 1

Pretty good agreement between DeShon and co’s “visuospatial” and Styles’ “equation” (both what does and doesn’t fall into these buckets).  The “equation” items concern those with “overlapping elements” – seems pretty visuospatial.  Also neither classification codes item 15: DeShon and co say it violates the task instructions.  The rest is a bit of a mess, but then Styles peeked at a higher resolution into the analytic items.

References

DeShon, R. P., Chan, D., & Weissbein, D. A. (1995).  Verbal overshadowing effects on Raven’s Advanced Progressive Matrices: Evidence for multidimensional performance determinants. Intelligence, 21, 135-155

Styles, I. (2008).  Linking Psychometric and Cognitive-Developmental Frameworks for Thinking About Intellectual Functioning.  In Raven, J. & Raven, J. (ed.), Uses and Abuses of Intelligence: Studies Advancing Spearman and Raven’s Quest for Non-Arbitrary Metrics. Royal Fireworks Press.

How to get someone’s g

“Intelligence”, “IQ”, “g” (due to Spearman), are terms that are bandied around.

The following may be helpful: the gist of how to calculate someone’s g score, which is often used as the measure of someone’s “intelligence”.

For example, that’s the “IQ”/”intelligence” referred to in the recentish BBC article on research linking childhood intelligence and adult vegetarianism (clever children grow into clever vegetarian adults).

  1. Give hundreds or thousands of people a dozen tests of ability.
  2. Zap everyone’s scores with PCA or factor analysis.
  3. g is the first component and usually explains around half the variance.  Here’s an example genre of analysis of g with other facets to psychometric intelligence.
  4. Use the component to calculate a score.  For factor analysis there are many ways to do this, e.g. Thompson’s scores, Bartlett’s weighted least-squares.  The gist is that for each person you compute a weighted sum of their scores, where the weights are a function of how loaded the particular test score was on g.
  5. To get something resembling an IQ score, scale it so it has a mean of 100 and an SD of 15.
  6. Talk about it as if it were a substantive psychological construct, rather than a statistical artefact 😉

What is this mysterious g thing?