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# st: Survival Analysis estat phtest with very large sample size--need help

 From prymkiewicz To statalist@hsphsun2.harvard.edu Subject st: Survival Analysis estat phtest with very large sample size--need help Date Thu, 5 Dec 2013 18:26:26 -0800 (PST)

```Hi,

I need a bit of help.

I am doing a survival analysis on a large population ~435732 people.  I have
been testing the PH assumption using estat phtest and schoenfled residuals.
I believe that the large sample size is causing the phtest indicate evidence
against the PH assumption while the schoenfeld plot would indicate that the
model variables adheres to the PH assumption. I have included the global and
individual variable tests, as well as the plot for one of our variables
(mets). Could you let me know the cause of this and could you let me know if
there are alternative methods or references in literature acknowledging the
phtest and alternative methods for very large study populations.

Thanks,
Peter

. estat phtest, detail

Test of proportional-hazards assumption

Time:  Time
----------------------------------------------------------------
|       rho            chi2       df       Prob>chi2
------------+---------------------------------------------------
male        |      0.01247        11.18        1         0.0008
age         |      0.05331       252.06        1         0.0000
0b.urban    |            .            .        1             .
1.urban     |     -0.01640        19.44        1         0.0000
99.urban    |     -0.00225         0.36        1         0.5472
1b.quintile |            .            .        1             .
2.quintile  |     -0.00620         2.74        1         0.0976
3.quintile  |     -0.00745         3.98        1         0.0461
4.quintile  |     -0.00025         0.00        1         0.9457
5.quintile  |     -0.00311         0.70        1         0.4039
99.quintile |     -0.00119         0.10        1         0.7499
mi_1        |     -0.00795         4.63        1         0.0314
chf_1       |     -0.02492        47.01        1         0.0000
pvd_1       |      0.00206         0.32        1         0.5734
cevd_1      |     -0.02076        32.80        1         0.0000
dem_1       |      0.00630         3.05        1         0.0807
copd_1      |     -0.01545        17.10        1         0.0000
rheum_1     |     -0.00840         5.06        1         0.0245
pub_1       |     -0.00712         3.67        1         0.0553
mildld_1    |     -0.00959         6.59        1         0.0102
diab_uc_1   |     -0.02159        34.32        1         0.0000
diab_c_1    |      0.01731        21.99        1         0.0000
para_1      |     -0.01532        17.14        1         0.0000
rd_1        |     -0.03307        82.48        1         0.0000
cancer_1    |     -0.03237        72.39        1         0.0000
mlsd_1      |     -0.00246         0.43        1         0.5099
mets_1      |     -0.06236       272.50        1         0.0000
hiv_1       |     -0.00863         5.31        1         0.0213
------------+---------------------------------------------------
global test |                   1392.71       26         0.0000
----------------------------------------------------------------

<http://statalist.1588530.n2.nabble.com/file/n7580460/phtest_plot_mets_1.jpg>

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