Reliability of a Utility for Risk Measure
Since the publication of Von Neurnann and Morgenstern's book (1944), risk-taking has received intensified attention as a factor in psychological behavior. Recently, Ziller (1957) has developed a technique for estimating utility for risk which supposedly measures individual decision-making response under conditions of uncertainty and risk. Ziller's Test Risk score is obtained by the following formula developed by him and Roby ( 1957 ) : R = 2\W/ ( 2 W + 0 ) , where R = Risk, W = Number of wrong responses, and 0 = Number of items omitted. The measure of utility for risk may then be described as the ratio of the number of items on which Ss hazard guesses to the number of items not known by Ss. However, the reliability of this type of measure has not been established. A 15-item quiz,l designed on the Ziller paradigm for an introductory psychology class at the University of North Dakota was administered to 279 students. Their scores from the odd-numbered items of the quiz were used in the Ziller formula in order to obtain Test Risk scores. The same procedure was followed, using information from the even-numbered items. A split-half reliability coefficient was computed, based on these two sets of Test Risk scores. The obtained split-half coefficient was .77, when corrected by the Brown-Spearman formula was 3 7 . The split-half technique generally is believed to result in spurious estimates of the reliability of a measure. However, the results suggest that chis parcicular measure possessed acceptable split-half reliability.