Assessment

To diagnose specific learning disabilities, assess attainments with standardized tests such as the WIAT-II or WRAT-3 (listed in Table 8.6) and intelligence with tests such as the WISC-IV or BAS-II (listed in Table 8.2). The attainment-ability score discrepancy method or observed-predicted attainment score discrepancy method may be used to evaluate the presence of a specific learning difficulty. With the attainment-ability score discrepancy method, if any attainment score falls 1.5 standard deviations (about 22 points) below the Full Scale IQ score, then a specific learning difficulty in that area may be diagnosed. The observed and predicted attainment score method can be used if there is a table in the manual of the attainment or ability test that gives expected attainment scores associated with IQ level. From such tables, predicted attainment levels may be determined. The statistical significance of discrepancies between predicted and observed attainment levels may be evaluated with reference to tables of such discrepancies given in the manual. For both procedures, there is an assumption that the child had cooperated well with testing procedures and has had adequate opportunity to develop reading skills.