On Wed, 8 Mar 2006, Paulo Brando wrote:
>
>> summary(model.fit) # just one species from one treatment shown below
>
> Call: survfit(formula = Surv(time, censo) ~ treatment + species, data =
> wsuv)
>
> treatment=0, species=1
> time n.risk n.event survival std.err lower 95% CI upper 95% CI
> 1 15440 386 0.975 0.00126 0.973 0.977
> 2 15054 336 0.953 0.00170 0.950 0.957
> 3 14668 302 0.934 0.00200 0.930 0.938
> 4 14282 296 0.914 0.00226 0.910 0.919
> 5 13896 281 0.896 0.00247 0.891 0.901
> 6 13510 264 0.878 0.00264 0.873 0.883
> 7 13124 251 0.861 0.00280 0.856 0.867
> 8 12738 232 0.846 0.00293 0.840 0.852
> 9 12352 216 0.831 0.00305 0.825 0.837
> 10 11966 206 0.817 0.00315 0.811 0.823
> 11 11580 190 0.803 0.00325 0.797 0.810
> 12 11194 179 0.790 0.00333 0.784 0.797
> 13 10808 167 0.778 0.00341 0.772 0.785
> 14 10422 167 0.766 0.00349 0.759 0.773
> 15 10036 145 0.755 0.00356 0.748 0.762
> 16 9650 142 0.744 0.00363 0.737 0.751
> 17 9264 135 0.733 0.00369 0.726 0.740
> 18 8878 122 0.723 0.00375 0.715 0.730
> 19 8492 99 0.714 0.00380 0.707 0.722
> 20 8106 84 0.707 0.00385 0.699 0.714
> 21 7720 68 0.701 0.00389 0.693 0.708
> 22 7334 66 0.694 0.00393 0.687 0.702
> 23 6948 51 0.689 0.00397 0.681 0.697
> 24 6562 40 0.685 0.00400 0.677 0.693
> 25 6176 38 0.681 0.00403 0.673 0.689
> 26 5790 37 0.676 0.00407 0.669 0.684
> 27 5404 33 0.672 0.00411 0.664 0.680
> 28 5018 31 0.668 0.00415 0.660 0.676
> 29 4632 26 0.664 0.00419 0.656 0.673
> 30 4246 22 0.661 0.00423 0.653 0.669
> 31 3860 15 0.658 0.00427 0.650 0.667
> 32 3474 14 0.656 0.00431 0.647 0.664
> 33 3088 14 0.653 0.00436 0.644 0.661
> 34 2702 13 0.650 0.00443 0.641 0.658
> 35 2316 12 0.646 0.00451 0.638 0.655
> 36 1930 11 0.643 0.00462 0.634 0.652
> 37 1544 12 0.638 0.00480 0.628 0.647
> 38 1158 10 0.632 0.00507 0.622 0.642
> 39 772 9 0.625 0.00557 0.614 0.636
> 40 386 8 0.612 0.00709 0.598 0.626
>
> I don't get why with 8 leaves remaining (out of 384), the survival is
> about 0.6???
>
It looks as though the majority of your leaves are censored, especially at
later time points. At each of your 40 time points about 1-2% of the leaves
under observation die, so the survival curve should end up somewhere
between 0.98^40 =0.45 and 0.99^40=0.67, and it does.
-thomas
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