Description 
Permutation test of the null hypothesis that a set of data was sampled from a symmetric distribution with a particular mean. The test is based on a tstatistic and can be applied to situations in which a one sample or paired sample/repeated measures ttest is appropriate. Note, that this test is more general than parametric ttests in that it does not assume that the data were sampled from a Gaussian distribution.
This function can perform the test on one variable or simultaneously on multiple variables. When applying the test to multiple variables, the "tmax" method is used for adjusting the pvalues of each variable for multiple comparisons (Blair & Karniski, 1993). Like Bonferroni correction, this method adjusts pvalues in a way that controls the familywise error rate. However, the permutation method will be more powerful than Bonferroni correction when different variables in the test are correlated.
References:
Blair, R.C. & Karniski, W. (1993) An alternative method for significance testing of waveform difference potentials. Psychophysiology.
