vartestn error line 272

Hi everyone,

I'm trying to make vartestn works but everytime I get :

Unrecognized function or variable 'testname'.

Error in vartestn (line 272)
   Table{k+4,1} = testname;

Error in Statistiques (line 69)
HO_ini(counter,1).data=vartestn([A';B'],'TestType','LeveneAbsolute')

Could someone help me to solve this problem ?

A part of my currently code if it could help :

HO_ini=vartestn([A';B'],'TestType','LeveneAbsolute')

Best,

Thibaut Deville.

Answer 1

[Chidvi Modala]

Are you trying to use the Levene's tests for data with a single group?

[Thibaut Deville]

No, I am not.

I have 6 groups to compare 1 to 1.

Here, some code to simulate my data and getting the same error :

%Data simulation
for i=1:2
    Test(i).data=rand(24,1);    %group 1-2
    Test(i+2).data=rand(17,1);  %group 3-4
    Test(i+4).data=rand(12,1);  %group 5-6
end
%%
%Levene's test
counter=1;
for i=1:5
    for j=1:5
        if i+j < 7
            %E_ini
            A=Test(i).data;
            B=Test(j+i).data;
            p(counter,1) = vartestn(A,B,'TestType','LeveneAbsolute');                
            clear A B 
            counter=counter+1;
        end
    end
end

[Chidvi Modala]

This is a bug. I have brought this issue to the notice of our developers and will try to fix it in future releases.

[Chidvi Modala]

The vartestn function wants data as the first input and grouping information as the second. It looks like you are supplying the first data sample as the first input and the second data sample as the second. May be you can change the code from

p(counter,1) = vartestn(A,B,'TestType','LeveneAbsolute');

to

p(counter,1) = vartestn([A;B],[zeros(size(A));ones(size(B))],'testtype','leveneabsolute')

Also the original line of code above is defining a series of single-observation groups. It is not possible to estimate the variance from single observations, so the vartestn is going into a piece of code to deal with this edge case of no information.