Logrank

Comparing survival curves of two groups using the log rank test

Description

Comparison of two survival curves can be done using a statistical hypothesis test called the log rank test. It is used to test the null hypothesis that there is no difference between the population survival curves (i.e. the probability of an event occurring at any time point is the same for each population). This function use the Kaplan-Meier procedure to estimate the survival function, so it is mandatory to download
KMPLOT (http://www.mathworks.com/matlabcentral/fileexchange/22293).

• Required Products: Statistics Toolbox
• MATLAB release: MATLAB 7.6 (R2008a)
• Other requirements: KMPLOT (http://www.mathworks.com/matlabcentral/fileexchange/22293).
• Other Files: license.txt, ; logrank.m, ; logrankdata.mat

[En Bl]

I get this error:
Matrix dimensions must agree.

Error in ==> logrank at 157
    K=find((table12(:,1)<table(c(I),1) & table12(:,1)>=table(J,1)),1,'last');

I debugged it and J=[] .

[Giuseppe Cardillo]

Perhaps, if you email me the data I can understand the error. I think that your input data matrix are in a wrong format.

[En Bl]

Here is the data:
x1 =
3010 1
1733 1
2797 1
334 0
3678 1
3314 1
4378 1
3253 1
1672 0
3709 1
1642 1
3040 1
2827 1
 and x2 =
1955 1
1808 1
2037 1
3136 1
938 0
3497 1
2858 1
3832 1
3256 0
2933 0
5054 1
927 0
3795 0
4155 1
3304 0

sorry for the late reply.

[Giuseppe Cardillo]

I have corrected the bug and uploaded the new version. Anyway, with all these censored data, it is difficult to assess differences....

[En Bl]

Thanks.

[the cyclist]

It seems to me that this function does not work for the case when none of the data are censored. (That shouldn't be a problem, should it?) For example, using only the first columns of your sample x1 and x2:

>> logrank(x1(:,1),x2(:,1))

causes a crash for me.

[Giuseppe Cardillo]

You are partially right. If you use only the first column, the routine crashes because the informations in the second column are mandatory. If you want no censored data:
>> x1(:,2)=0; x2(:,2)=0; logrank(x1,x2);

Anyway, a bug was present but I fixed it and upload the new version.

[the cyclist]

Thanks for the really quick reply. I appreciate it.

However, the program still crashes for me, with the same error, when I try the syntax you suggest. Maybe the version on the File Exchange is not quite the same as yours?

[Giuseppe Cardillo]

At the moment, there is not on FEX the new uploaded file (this takes 1-2 days). If you contact me in private, I'll send you the file as an attach