The boot function documentation says, "The data as a vector, matrix or data frame. If it is a matrix or data frame then each row is considered as one multivariate observation". From trying several things, I've concluded that this means it resamples the rows but calculates the statistic on the columns. For example, if I apply boot with var as the statistic to a data set with the following column names Sample, ID, Period, Plot, and Species, I will get the variance for Sample, ID, Period, Plot, and Species based on the resampled rows. I have a function that operates on an entire row. That is, it calculates a statistic for Species, with in a Sample, ID, Period and Plot combination. Is there a way to use such a function as the statistic in the boot function? Christina D Smith PhD Student, GRA Statistics Department Kansas State University