The following fit does not make sense to me, please, correct me if I have a logical error.

> moddowsn
Call:
coxph(formula = Surv(start, stop, resp) ~ sn + matfac2, data = coxsn1,
    method = "efron")


            coef exp(coef) se(coef)       z       p
sn2       0.0497     1.051  0.02030   2.450 1.4e-02
sn3      -0.0532     0.948  0.02038  -2.610 9.0e-03
sn4      -0.0410     0.960  0.01979  -2.073 3.8e-02
sn5      -0.0776     0.925  0.01954  -3.973 7.1e-05
sn6      -0.1133     0.893  0.01839  -6.161 7.2e-10
sn7      -0.1252     0.882  0.01846  -6.781 1.2e-11
sn8      -0.1222     0.885  0.01994  -6.130 8.8e-10
sn9      -0.0507     0.951  0.02047  -2.478 1.3e-02
sn10     -0.0444     0.957  0.02056  -2.159 3.1e-02
sn11     -0.0433     0.958  0.02157  -2.008 4.5e-02
sn12     -0.0114     0.989  0.02037  -0.557 5.8e-01
matfac22 -0.2599     0.771  0.01727 -15.048 0.0e+00
matfac25 -0.1804     0.835  0.00924 -19.512 0.0e+00

Likelihood ratio test=651  on 13 df, p=0  n= 253802

This would indicate that in sn6 to sn8 there is less of a chance of an event. ?? do the relative frequencies implied by the following table make any sense??

> table(coxsn1$matfac2,coxsn1$sn,coxsn1$resp)
, ,  = 0


        1     2     3     4     5     6     7     8     9    10    11    12
  1  3407  3177  3425  3348  3975  3564  3181  3077  2894  2610  3441  3443
  2   920  1005  1142  1327  1645  1530  1330  1184   964   864   888   860
  5  9036  9507 10258 11888 16826 15575 13394 12346  9938  9001  8970  8599

, ,  = 1


        1     2     3     4     5     6     7     8     9    10    11    12
  1  1453  1459  1186  1496  1295  1754  1429  1153  1106  1234   965  1532
  2   312   290   330   390   454   539   479   367   295   276   256   267
  5  2994  3207  3371  3629  4095  5581  5837  3844  3400  3199  2705  3084

Apparently the frequency of an event is higher in the summer months.
I apologize for not being able to disclose the dataset, but think that the table provides enough to address the question.
Thanks everybody.


Stephen B

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