Hello everyone,
I am about to embark on a Cox Regression in SPSS. However, I have some
questions about the output. If we take the hypothetical data set below
Age sex time death
1.00 1.00 10.00 1.00
.00 1.00 12.00 .00
.00 .00 12.00 1.00
1.00 .00 21.00 .00
.00 1.00 45.00 1.00
.00 1.00 21.00 .00
.00 1.00 .00 .00
1.00 .00 2.00 .00
1.00 .00 1.00 .00
1.00 .00 4.00 1.00
1.00 .00 3.00 1.00
.00 .00 67.00 1.00
.00 1.00 33.00 1.00
.00 .00 21.00 1.00
.00 1.00 2.00 .00
1.00 .00 22.00 1.00
1.00 1.00 1.00 .00
1.00 .00 6.00 .00
1.00 .00 5.00 1.00
.00 .00 3.00 .00
.00 .00 2.00 1.00
.00 .00 7.00 .00
.00 1.00 55.00 1.00
1.00 1.00 3.00 1.00
1.00 1.00 1.00 .00
I have entered in the dialogue box that Sex and Age are the covariates,
'time' is the 'time' variable and 'status' is variable named death (with
'1' as the event).
I find in the output that 4 cases have been omitted. There is 1 case
omitted with 'non positive' time. What does this mean? There are 3
cases which have been omitted which are 'censored cases before the
earliest event in a stratum'...what does this mean? Hence the means
printed for sex and age are 0.381 and 0.429 respectively. I would be
grateful if you could tell me how these values have been evaluated.
Also (for another data set (where I run a Kaplan Meier analysis the
following message is printed:
>"A negative or missing value of dependent variable has been
encountered. KM
>will exclude such cases from analysis".
What does this mean?
The SPSS manuals do not seem to be very enlightening on this point.
Many thanks,
Kim
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