Army ants algorithm for rare event sampling of delocalized nonadiabatic transitions by trajectory surface hopping and the estimation of sampling errors by the bootstrap method Abstract. The pseudo-median procedure is a technique for treatment group comparison which adopts the pseudomedian as a location parameter. The power of this procedure is estimated in various shapes of distributions and different degrees of variation. The bootstrap method is employed to generate the approximate sampling distribution of the statistic. The results show that the power of this procedure is not affected by the shape of the data. However, the power is affected somewhat by the heterogeneity of variances.