This investigation was conducted to explore the between trial variability of the measures of the isometric peak force, time to peak force, area to peak force, area under the curve, slope (20%-80%), and the average slope of subjects assigned to perform a series of four isometric grip strength contractions and to develop a discriminant function equation that would predict group membership. Forty-nine college students were instructed to perform either a series of four maximal voluntary contractions (sincere) or a series of four submaximal (deceptive) contractions. The subjects were retested 24-48 hours after the initial test session. Data from both test sessions were recorded, displayed, and analyzed using segmental curve analysis. The coefficients of variation were computed for each test variable. The grand mean coefficient of variation for the sincere condition was .31 ± .02 compared to the grand mean coefficient of variation for the deceptive condition which was .77 ± .11 (p < .01). Coefficients of variation were used to predict group membership. The prediction equation accurately classified 92% of the sincere condition and 64% of the deceptive condition.