Table 6: Model development versus items.

(a)

Regression statistics Multiple R 0.4817 R Square 0.2320 Adjusted R square 0.2046 Standard error 22.5342 Observations 88.0000

(b)

ANOVA df SS MS F Significance F Regression 3.0000 12886.4152 4295.4717 8.4592 0.0001 Residual 84.0000 42654.2098 507.7882     Total 87.0000 55540.6250

(c)

Coefficients Standard error t stat P value Intercept 14.0351 11.7183 1.1977 0.2344 Arith Manip 1.0878 0.2741 3.9689 0.0002 Algebra 0.8736 0.2504 3.4886 0.0008 ManipXAlg −0.0153 0.0047 −3.2345 0.0017