What type of multiple comparisons is used in multcompare?

Hi everybody,

I've used the following function after performing Kruskal Wallis test:

c = multcompare(KW_stats(1,1).name)

Does anyone know what type of multiple comparisons is used? FDR, Bonferroni?

Best,

Eric

Answer 1

[Qu Cao]

Hi Eric,

You can specify the type of comparison as documented at the following link:

http://www.mathworks.com/help/stats/multcompare.html#input_argument_namevalue_ctype

The default type is 'tukey-kramer'.

Thanks,

Qu

[Lingyun GUO]

Dear Cao:

I want to ask ：

I have 3 sets of data. It has been organized into two columns The first column is basedata; The second column is the grouping basis.

G1(:,1)=rand(30,1);

G1(:,2)=1;

G2(:,1)=rand(32,1);

G2(:,2)=2;

G3(:,1)= rand(30,1);

G3(:,2)=3;

X=[G1;G2;G3]; % size is (92*2).

[P,anovatab,stats] = kruskalwallis(X(:,1),X(:,2));

c2=multcompare(stats);

The answer is:

1 2 -18.21 -2.31 13.60 0.94

1 3 -11.96 4.20 20.36 0.82

2 3 -9.40 6.51 22.41 0.60

In order to verify that the data is accurate, I continued to carry out two separate KW test data.

A= [G1;G2];

[P,anovatab,stats] = kruskalwallis(A(:,1),A(:,2));

c2=multcompare(stats);

The answer is:

1 2 -10.34 -1.35 7.63 0.77

Got the p value of their difference. Why, Which p value can truly reflect the difference between G1 and G2?

I'm looking forward to your reply very much.