A function to perform a permuted difference test on two numeric vectors
Three arguments: a = dataset 1 (vector, numerics) b = dataset 2 (vector, numerics) alpha = test statistic (0.05 by default)
outputs:
'pvalue'= pvalue 'p-value is the fraction of how many times the permuted difference is equal or more extreme than the observed difference'. 'permutedmean'= Mean of differences between means of permuted datasets. 'result'= the result of the hypothesis test 'under the null hypothesis, there is no difference between the two groups'. 'basedata'= dataset 1 'testdata'= dataset 2 'alpha'= test statistic