Permutation test for variability: Is my analysis correct?

Concerning the paper: Permutation Tests for Comparing Two Populations, Journal of Mathematical Sciences & Mathematical Education, Vol. 3 No.3, pg 25, Ferry Butar Butar, Ph.D., Jae-Wan Park

There are two kinds of product inspectors: A (not-experienced) and B (experienced) and after each had inspected 200 items, their work was checked and the errors counted:

A: 30, 35, 26, 40, 36, 20, 45, 31, 33, 29, 21, 48
B: 31, 15, 25, 19, 28, 17, 19, 18, 24, 10, 20, 21


the means are mA=32.83, mB=20.58 , d0=12.25.

In order to get a more vivid picture I ordered the data

A: 20, 21, 26, 29, 30, 31, 33, 35, 36, 40, 45, 48
B: 10, 15, 17, 18, 19, 19, 20, 21, 24, 25, 28, 31


The Authors use a permutation test of the variability (based on the median of samples) and claim that "there was not difference relative to the number of mistakes", but I do not agree.

a) Based on 40´000 permutations for each sample I found that [18.90, 22.26] contains 95% of the Population differences corresponding to the 0.025, 0.975 quantiles. Therefore, d0=12.25 is outside

b) I performed www.socscisstatistics.com/tests/mannwhitney/default2.aspx U-value = 14.5 under critical 5% signifiance, two-tails, = 37 Z-score,p-value= 0.001.

Am I wrong?

They then go on to calculate The ratio of median deviance for the original observations etc. I don't think you've been calculating the proper things.