set.seed(910401)
distr_data <- rgamma(100,0.1,1)

wilcox.test(distr_data, conf.int = T)
# 0.006787143

all_pairs <- t(combn(distr_data, 2))
all_pair_means <- (all_pairs[,1] + all_pairs[,2]) / 2
median(all_pair_means)
# 0.006970087

distr_data <- rgamma(100,0.1,1000)

wilcox.test(distr_data, conf.int = T)
# 6.533661e-05
# CI 6.049175e-05 8.016369e-05

all_pairs <- t(combn(distr_data, 2))
all_pair_means <- (all_pairs[,1] + all_pairs[,2]) / 2
median(all_pair_means)
# 9.181717e-06