Table 2 Intellectual efficiency: Hedge’s g effect sizes for each test, in descending order.

Verbal

National adult reading test

7

210

164

− 0.07

0.11

− 0.272 to 0.140

0.533

7.35

0.29

18.40

Cockshell et al.¹⁷, Di Clementi et al.⁵⁷, Fiedler et al.²⁴, Joyce et al.²⁹, Lawrie et al.³¹, Marshall et al.³⁵, Robinson et al.⁴⁴

WAIS-R Verbal

2

34

33

− 0.10

0.24

− 0.571 to 0.364

0.664

0.03

0.86

0.00

Claypoole et al.¹⁵, DeLuca et al.²⁰

Non-verbal

Standard progressive matrices

3

84

77

− 0.17

0.16

− 0.476 to 0.136

0.276

0.50

0.78

0.00

Michiels et al.^39,40,41