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Test Development / Validity

Regardless of age or gender, persons with ADHD persons exhibit a subset of a range of similar behaviors. It is the theoretical foundation with respect to the description/manifestation of these behaviors which guide in the selection of the items which constitute the C-ADDS.

Interrelationship Among C-ADDS Subtests

A common way to study test’s validity is to inspect the inter-correlation among the subtests. Since all the C-ADDS items are intended to measure ADHD behaviors, one would expect to find strong inter-correlations between/among them. The results of the correlations of the C-ADDS subtests indicate that all of the correlations are significant and quite large in magnitude. Analyses of the data demonstrate strong inter-correlations or strong relationships with each other; an indication that the items in each subtest are measuring the same construct... the behavioral characteristics of ADHD.

High construct validity leads to high item discrimination ability. The high point-biserial correlation of each item to its respective subtest indicates that the test items are making strong contributions to the construct(s) being measured.


The C-ADDS is a highly standardized norm-reference instrument designed for use by trained teachers, psychologists, counselors, social workers, and others for the purpose of screening for ADHD. It was developed through empirical and logical techniques and was norm on a sufficiently large sample of persons who have the diagnostic characteristics for whom the test will be utilized in the future. The quality of the C-ADDS was confirmed through pilot studies, correlation analyses, and tests of reliability and validity.The reliability of the test is well within an acceptable range. The internal consistency and reliability of the subtests were determined to be in the (80's and 90's). Studies of both test-retest and inter-rater reliability confirm the C-ADDS utility as a diagnostic screening instrument.

The validity of the C-ADDS was demonstrated through a series of analyses. These analyses confirmed that (a) the items of the C-ADDS are representative of the characteristics of ADHD; (b) the scores are strongly related to each other and to ratings on other scales that screen for ADHD; and (c) the C-ADDS can discriminate persons with ADHD from the general population.