Development, cross-validation, and assessment of reliability of the Christensen Dietary Distress Inventory.

Abstract
A series of two studies was conducted to develop and cross-validate a psychometric instrument capable of identifying individuals experiencing a dietary induced mood disturbance. The first study focused on the development of the Christensen Dietary Distress Inventory (CDDI) by identifying the items which would differentiate dietary responsers from nonresponders. Dietary responders were identified as those individuals whose mood disturbance improved following a dietary intervention and deteriorated following either a return to their typical die or following a challenge of refined sucrose or caffeine as opposed to placebo or aspartame. The results revealed that 34 CDDI items differentiated dietary responders from the nonresponders. The test-retest reliability of this scale was 87. The second study cross-validated the CDDI. Using an A-B single-subject design and double-blind challenges, seven of 23 research participants were identified as definite dietary responders, nine as definite dietary nonresponders, and seven as probable dietary responders. The dietary responders'' and nonresponders'' CDDI scores were significantly different and a point-biseral of .48 existed between the subjects'' CDDI score and their group categorization. Such data indicate that the CDDI is a valid psychometric instrument. Inspection of the sensitivity and specificity indices indicates that a cutoff score of 13 results in the selection of the most true positives with the least number of false positives.

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