Exact t-test for 2 independent samples
Exact t-test for 2 independent samples.
exact.ttest2(x, y)
x |
A numerical vector with the data. |
y |
A numerical vector with the data. |
This function performs an exact t-test. With few observations, permutation or bootstrap calculation of the p-value is advisable. However, with even fewer observations, one can perform all possible permutations and calculate the exact p-value. This is what this function does. BUT, pay attention, as this works with few samples. If for example each sample contains 15 numbers, you will need a lot of memory (more than 17 GB) for this function to work. the reason is that we create the matrix with all possible permutations first and then perform the two-sample t-test.
A vector with the number of permutations, test statistic and the permutation based p-value.
Michail Tsagris and Manos Papadakis
R implementation and documentation: Michail Tsagris <mtsagris@yahoo.gr> and Manos Papadakis <papadakm95@gmail.com>
B.L. Welch (1951). On the comparison of several mean values: an alternative approach. Biometrika, 38(3/4), 330-336.
x <- rnorm(7) y <- rnorm(7) res<-exact.ttest2(x, y)
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