Nonparametrical statistical mapping

Statistical mapping is widely used in electrophysiological research. T-statistic mapping is commonly used in between-group map comparison. The t-map, which is based upon the equal variance of groups, was the first type of statistical mapping to be used in this field. Later, a t-map, and a p-map using the unequal variance hypothesis were introduced. Although, the latter is more adequate for comparisons where the variance of both groups cannot be assumed to be equal. Its use is not appropriate in the case where the respective distributions of the populations are not normal. To face this situation, we introduce a new kind of statistical mapping based upon nonparametric tests. This type of mapping corresponds to a distribution-free test in the sense that the population distribution is not assumed to be normal. This technique therefore increases the degree of freedom of the researcher when comparing groups with a non-normal, or more generally an unknown distribution