No other validity data are reported for this instrument. Coefficient alpha estimates of reliabilities for the Tolerance scale were .76 and .87 for the Quality of Relationships scale. A four month test-retest stability coefficient was reported as .66 for the Tolerance scale and .68 for the Quality of Relationships scale. Longer term test-retest reliability measures were .44 for the Tolerance scale and .72 for the Quality of Relationships scale. The correlations between the two scales was .25 suggesting that they measure somewhat different constructs.
Studies conducted did indicate construct validity for the dimensions assessed by the inventory.
However, additional research is needed to prove the validity of this instrument. The purpose of the Parker Cognitive Development Inventory is to measure stages of cognitive development. The Parker Cognitive Development Inventory is one of six inventories designed to assess student development. While six of the inventories are designed to measure student development according to Chickering's vectors of student development, the Parker Cognitive Development Inventory was developed to measure cognitive development according to the Perry scheme. Reliability coefficients for the nine subscales range from .64 to .87.