Quality is an overall test measure, derived from robustness (rob), validity (val), reliability (rel), hardness (hard), resolution (res) and quality of norms (norm) as follows:
Test quality = √((rob2 + val2 + rel2 + hard2 + res2 + norm2) / 6)
As a measure of validity, the estimated g factor loading is used in the case of intelligence tests. When one or more of the statistics is or are missing they may be left out and the divider adjusted appropriately.