Non-Parametric Two-Sample Test

A marine mammalogist is comparing the life histories of two different species of seals. In particular, she wants to know how their age distributions differ, if at all. Age distributions are notoriously non-normal, as there are often many young animals, and relatively few very old ones. Using dentine layers, she is able to determine the following ages for seals of each species:

Seal species A: 3, 4, 2, 6, 5, 8, 2, 5, 3, 12

Seal species B: 3, 5, 6, 8, 2, 4, 9, >16, 11

At a = 0.10 do the age distributions appear to be centered on the same value?

I got R_A = 86.5 and R_B = 103.5. Note that 86.5 + 103.5 = 190 = 19(20)/2. Oh, good.

Next, I found U_A = 58.5 and U_B = 31.5. U_max = 58.5.

The critical value is U_{0.10(2), 9, 10} = 66. Our observed test statistic is less that the critical value, so we fail to reject the null hypothesis and conclude that the age distributions are likely centered at the same value.