Comparison of four short forms of the French adaptation of the Wechsler Adult Intelligence Scale – Fourth Edition (WAIS-IV)

Introduction The Wechsler Intelligence Scale for Adults - 4th Edition (WAIS-IV) is widely used in France and French-speaking countries for clinical assessment and research. This scale has excellent metric qualities; there is ample evidence of the validity and reliability of its scores. However, it takes 60 to 90 min to complete the full test. That can be problematic in research where time is limited and when examining very disturbed patients. In such cases, a short form of the WAIS-IV may be useful. Unfortunately, no short form of the French version of WAIS-IV has yet been validated using the standardization sample. Objective The aim of the present study was to identify an abbreviated form of WAIS-IV with sufficient validity and reliability to replace, in some cases, the full test. Method Four short forms were developed taking into account the fidelity and the correlation with the FIQ of the subtests included in each of form. The metric qualities the four short forms were compared using the standardization data of the French WAIS-IV. The standardization was done using the results of a sample of 876 individuals representative of the French population from 16 to 79 years 11 months. Results The analyzes showed that a short form including Information, Matrices, Arithmetic and Code provides a fairly good estimate of the FIQ. The fidelity of the estimated IQ was 0.94 and its correlation with the FIQ was 0.91. However, the average of the absolute differences between the IQ calculated with this short form and the IQ calculated with the full form was 4.24 points, with a standard deviation of 3.15 points. These differences could lead to misidentification of some individuals tested with the short form. Conclusion The proposed short form provides a sufficient approximation of the FIQ to be used in research where the collective results are more important than those of individuals. This short form, however, does not provide an IQ measure as robust as the full form. It should therefore be used with caution only when using the full form is not possible.