Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
st: Cubic splines in stcox
From
Marc Peters <[email protected]>
To
[email protected]
Subject
st: Cubic splines in stcox
Date
Fri, 4 Jan 2013 10:42:09 -0600
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
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/faqs/resources/statalist-faq/
* http://www.ats.ucla.edu/stat/stata/