"visualizing" Post hoc pairwise comparisons

[timspier]

I have a problem that I think is more of a "logic" problem than a VBA problem, but I need to solve it in VBA in Excel.

I have written a macro that calculates a Kruskal-Wallis nonparametric test. If this test is significant, it runs nonparametric post hoc pairwise comparisons to see which groups are significantly different. This all works without a hitch.

However, I am having trouble outputting the results. I create a matrix of all comparisons, and if the comparison is significant it marks that pair with an asterisk. I wish to modify that so it shows the results like you would get from a statistical package like SAS or SPSS. That is, I want all groups that are not significantly different to have the same letter.

For example, say I'm comparing the height of 4 different corn hybrids. The K-W test says that there is a significant difference between the groups, but I must run the post hoc test to see if groups 1 & 2 are different, 1 & 3 are different, 1 & 4 are different, 2 & 3 are different, 2 & 4 are different, and / or 3 & 4 are different.

Say my results come out like this: 1 is significantly different from all other groups, 2 is different from 1 & 4, 3 is different from 1, and 4 is different from 1 & 2. Thus, my groupings look like this:

1 A
2 B
3 B, C
4 C

See how the letter groupings show significance? And, see how the groups can overlap, so that although 2 is different from 4 and no different from 3, 3 is no different from 4? See how this can make me insane?

So, the question is, how can I come up with a logical method for assigning the letters? Right now, I do it by hand, and I usually get it right by just looking at the groups, but I know that there must be a logical way (because the stat software does it). Doing it by hand gets really tough with more groups and more overlap. Plus, I want a logical way of organizing these comparisons that I can show my students. Any ideas?

[The Dirt Dude]

I have the same problem. I have 16 pairwise comparisons to make, on 8 different figures. Any solutions to this?

[arlu1201]

The Dirt Dude,

Unfortunately you need to post your question in a new thread, it's against the forum rules to post a question in the thread of another user. If you create your own thread, any advice will be tailored to your situation so you should include a description of what you've done and are trying to do. Also, if you feel that this thread is particularly relevant to what you are trying to do, you can surely include a link to it in your new thread.