Dear Statalist users,
I am new to event history models and am estimating a Cox proportional
hazard model, with civil war as the dependent variable. the dependent
variable is measured at discrete intervals (yearly).
My basic model is estimated using the following syntax:
stset year, failure(cwar)
stcox dem gdp, cluster (country)
This model runs well, but I encounter problems when including cubic
splines, using this syntax:
mkspline sp_year=year, cubic nknots(3)
stcox dem gdp sp_year*, cluster (country)
When running the command I get the following message "flat region
resulting in a missing likelihood"
I am sure this is a very trivial question, but I would greatly
appreciate if anyone could help me in explaining what the problem is
and how I might fix it.
Thank you,
Marc
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