Complex sentence: In this case, one has to calculate the estimated standard deviation for each pairwise comparison as formalized by Clyde Kramer, so the procedure for unequal sample sizes is sometimes referred to as the Tukey-Kramer Method.
Split into simpler sentences: In this case, one has to calculate the estimated standard deviation for each pairwise comparison. The Tukey procedure for unequal sample sizes is sometimes referred to as the Tukey-Kramer Method.