Squared error of the mean calculated as
$$ \textrm{mean}(\textrm{observed} - \textrm{mean prediction})^2 $$ The mean prediction is calculated as the mean of the predictive samples.
Examples
observed <- rnorm(30, mean = 1:30)
predicted_values <- matrix(rnorm(30, mean = 1:30))
se_mean_sample(observed, predicted_values)
#> [1] 0.541860930 9.800234601 0.517696633 1.551587018 4.105700572
#> [6] 0.012761648 1.907995082 0.025050300 0.452778345 0.191431693
#> [11] 15.568627620 0.172518749 1.291851568 3.101428037 0.837992802
#> [16] 1.460835744 0.071220889 0.229046104 2.407846715 1.770079557
#> [21] 0.864783947 0.009872220 0.702369741 3.232846492 0.009438926
#> [26] 1.573558319 7.414888478 0.216364592 4.113449709 3.146478871