  Re-sampling based statistical tests are known to be computationally heavy,
but reliable when small sample sizes are available. Despite their nice
theoretical properties not much effort has been put to make them efficient. In
this paper we treat the case of Pearson correlation coefficient and two
independent samples t-test. We propose a highly computationally efficient
method for calculating permutation based p-values in these two cases. The
method is general and can be applied or be adopted to other similar two sample
mean or two mean vectors cases.
