The perception of aggression by nurses: psychometric scale testing and derivation of a short instrument.

Patient aggression is a serious problem in psychiatric nursing. Nurses' attitudes towards aggression have been identified as mediating the choice of nursing interventions. To date, investigations are lacking which elucidate the stability of one of the few scales for measuring the attitude of aggression. This study aimed to investigate the test-retest stability of the Perception of Aggression Scale and to derive a shortened version. In order to test the reliability of the Perception of Aggression Scale items, three groups of psychiatric nurses were requested to fill in the Perception of Aggression Scale twice (30 student nurses after 4 days, 32 qualified nurses after 14 days and 36 qualified nurses after 70 days). We derived the shortened version from an independent data set obtained from 729 psychiatry nurses using principal component analysis, aiming to maximize parsimony and Cronbach's alpha. Amongst competing short versions, we selected those with the highest reliability at 70 or 14 day retest. A scale using 12 of the original 32 items was derived yielding alphas of r = 0.69 and r = 0.67 for the two POAS factors with retest reliabilities of r = 0.76 and r = 0.77. The shortened scale offers a practical and viable alternative to the longer version.