Logrank

Very useful, but I had two questions. (1) LogRank gives an error at line 116, at [table1 table12 t1 T1 xcg1 ycg1 lambda1]=kmplot(x1,0.05,cflag,0);
This is fixed by deleting the last arg to kmplot, giving kmplot(x1,0.05,flag);

2) The p-value for LogRank is twice what it should be? 0.03058 vs. 0.01529 in the file header. Perhaps, mismatch between old documentation and changed function, or extra factor of 2 in p = 2*(1-0.5*erfc(-z/realsqrt(2))); %p-value

Removing Yates' gives 0.019250, which is correct. I tend to think 0.03058 is correct, with the Yates' correction. Thanks for the super-useful code!

The logrank calculation here is correct. This code applies the Yates correction in the calculation of the z-score. (Line 207 of my version of the code.) I get 0.0193 from this code when I remove the Yates correction.

I'm sorry, but using your software I do not get the p-value for the log-rank test that is consistent with the results of either R or Stata (both of which match). For the test data supplied with the function, I get a p-value of 0.0193, whereas you're getting a p-value of 0.01529. The KM curves are the same, but there is apparently something wrong in your logrank computation.

Is there a way to retrieve the Hazard ratio from the output of Logrank or Kmplot function?

I notice that in the call to kmplot [lines 96-97] in current version, the hard-coded value 0.05 is used, even if alpha is specified differently as an input. Is that correct?

Excellent submission - thank you. One note: the outputs to the function [T1,T2] are actually cleared during computation, so an error is thrown if output is requested. To conform a little bit to the MATLAB stats package, I suggest the following changes:

Line one should change to:
function [h,p] = logrank(varargin)

and the end of the function should set h as follows:
h = p<alpha;

The help section could then say:
% Displays:
% Kaplan-Meier plot
% Log-rank statistics
% Outputs:
% H : statistical significance (true if P<ALPHA)
% P : P-value for log-rank test

Beautiful, thanks for sharing this. If we use your software for a journal purpose, what reference should we use?

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

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.

Thanks.

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.

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=[] .