A permutation test is a statistical method used to determine if there is a significant difference between two groups. It works by rearranging the data points in the groups to create a distribution of possible outcomes. This allows researchers to compare the observed difference to the distribution of differences that could occur by chance. In a permutation test, the null hypothesis assumes that the groups are similar. By repeatedly shuffling the data and calculating the test statistic, researchers can estimate the probability of observing the actual difference. If this probability is low, it suggests that the difference is statistically significant.