[Narcissism inventory-90 (NI-90). Empirically-based reduction and identification of items sensitive for change--a questionnaire particularly suited for measuring self-regulatory parameters].

By analysing Narcissism Inventories [1] gathered by the admission from 639 consecutive in-patients, as well as a related sample of inventories gathered from 397 consecutive patients (7/93-7/96) by admission and discharge, we examined the possibility of reducing the number of items of the Narcissism Inventory without losing significant information. This examination shows that reducing the inventory to a total of 5 items per scale is reasonable, without a relevant loss of metric quality in the item-reduced scales. In addition, items particularly sensitive to change could be identified and pointedly kept in the new, reduced scales. Through the deliberate selection of these items, it was possible to produce an empirically-guided short-version of the Narcissism Inventory, suited particularly for the examination of clinical process and regulatory parameters. With persistence of the original 18 scales proposed by the authors of the original test, a reduction to a total of 90 items results. The name "Narcissism Inventory-90 (NI-90)" is, therefore, suggested for this new version.