Apologize for insufficient info in my previous version of this question. So, I am comparing patient survival in a retrospective study between two different groups, using SPSS. Now the difference came significant by KM, so I tried to adjust multiple covariates for confounding effect in a Cox model. I did a backward Wald test by putting main group in block 1 and co-variates in block 2. The output window gave me this:
Case Processing Summary
N Percent
Cases available in analysis Event 6065 10.3%
Censored 24860 42.1%
Total 30925 52.3%
Cases dropped Cases with missing values 28189 47.7%
Cases with negative time 0 0.0%
Censored cases before the earliest event in a stratum 0 0.0%
Total 28189 47.7%
Total 59114 100.0%
Dependent Variable: patient survival time (days)
Omnibus Tests of Model Coefficients
-2 Log Likelihood
115511.442 Omnibus Tests of Model Coefficientsi
Step -2 LL Overall (score) Change From Prev Step Change From Prev Block
Chi-square df Sig. Chi-square df Sig. Chi-square df Sig.
1a 113504.047 1998.887 23 .000 2006.433 22 .000 2006.433 22 .000
2b 113504.119 1998.833 21 .000 .072 2 .965 2006.361 20 .000
3c 113504.185 1998.423 19 .000 .066 2 .968 2006.295 18 .000
4d 113504.302 1998.059 17 .000 .118 2 .943 2006.177 16 .000
5e 113506.039 1996.799 15 .000 1.737 2 .420 2004.441 14 .000
6f 113507.146 1986.667 14 .000 1.108 1 .293 2003.333 13 .000
7g 113516.047 1978.462 7 .000 8.900 7 .260 1994.433 6 .000
8h 113518.520 1972.010 6 .000 2.473 1 .116 1991.960 5 .000
aStep 8 TX_MONTHJ 0.011 0.026 0.183 1 0.669 1.011 0.961 1.063
AGE 0.043 0.001 1483.638 1 0 1.044 1.042 1.047
AGE_GROUP 0.701 0.119 34.677 1 0 2.015 1.596 2.544
AGE_DON 0.006 0.001 56.755 1 0 1.006 1.004 1.007
NDIAL2_TRR(1) 0.129 0.041 9.873 1 0.002 1.138 1.05 1.233
I interpret this as saying that no difference was observed, but I'm confused about what to report. Could you also verify if this test looks good with the likelihood ratio so big?
Best Answer
If you are writing a paper, the journal probably has a style guide. Often, these show what to report. (This is assuming your question is mostly about which statistics to report and how to report them, not how to do the analysis).