2 Right Censoring and Kaplan-Meier Estimator - NCSU Statistics
2 Right Censoring and Kaplan-Meier Estimator - NCSU Statistics
2 Right Censoring and Kaplan-Meier Estimator - NCSU Statistics
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CHAPTER 2 ST 745, Daowen Zhang<br />
Note that the number of observed events <strong>and</strong> withdrawals in [ti−1,ti) were entered after ti−1<br />
instead of ti. Part of the output of the above SAS program is<br />
The LIFETEST Procedure<br />
Life Table Survival Estimates<br />
Effective Conditional<br />
Interval Number Number Sample Probability<br />
[Lower, Upper) Failed Censored Size of Failure<br />
0 1 27 3 144.5 0.1869<br />
1 2 18 10 111.0 0.1622<br />
2 3 21 10 83.0 0.2530<br />
3 4 9 3 55.5 0.1622<br />
4 5 1 3 43.5 0.0230<br />
5 6 2 11 35.5 0.0563<br />
6 7 3 5 25.5 0.1176<br />
7 8 1 8 16.0 0.0625<br />
8 9 2 1 10.5 0.1905<br />
9 10 2 6 5.0 0.4000<br />
Conditional<br />
Probability Survival Median<br />
Interval St<strong>and</strong>ard St<strong>and</strong>ard Residual<br />
[Lower, Upper) Error Survival Failure Error Lifetime<br />
0 1 0.0324 1.0000 0 0 3.1080<br />
1 2 0.0350 0.8131 0.1869 0.0324 4.4265<br />
2 3 0.0477 0.6813 0.3187 0.0393 5.2870<br />
3 4 0.0495 0.5089 0.4911 0.0438 .<br />
4 5 0.0227 0.4264 0.5736 0.0445 .<br />
5 6 0.0387 0.4166 0.5834 0.0446 .<br />
6 7 0.0638 0.3931 0.6069 0.0450 .<br />
7 8 0.0605 0.3469 0.6531 0.0470 .<br />
8 9 0.1212 0.3252 0.6748 0.0488 .<br />
9 10 0.2191 0.2632 0.7368 0.0558 .<br />
Here the numbers in the column under Conditional Probability of Failure are the es-<br />
timated mortality �m(x) =d(x)/(n(x) − w(x)/2).<br />
The above lifetable estimation can also be implemented using R. HereistheR code:<br />
> tis ninit nlost nevent lifetab(tis, ninit, nlost, nevent)<br />
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