Dear all,
i am a student of international relations and I have one short question for
you:
I am working with a tscs- structured dataset and I am computing a logit
modell with natural cubic splines following Beck, Katz and Tucker (1998) to
control for time dependency. I used the - btscs- package to generate the
necessary variables spellcount and _spline*
The command is as usual:
logit depvar idepvar1 idepvar2 ... spellcount _spline1 _spline2 _spline3,
vce(robust)
I now want to compute perdicted probabilities with - prvalue - .
My main question is, how to set the values of the variables spellcount and
spline1 - spline3? Does it really make sense to set them on their mean? Or
e.g. should I take the mean duration time until the analysed event occurs
and set the splines accordingly to that value? (For example if the mean
duration time is 5, then using - prvalue- I could set the spellcount on 5
and set the splines on the values which were computed by - btscs - for a
duration time of 5.)
Is there any good procedure for setting the splines on meaningful values so
that you can interpret the perdicted probabilities in a meaningful way?
I already had a look on some publicated articles in which also splines and
btscs- procedure were used. Most of them set the splines on their means, but
I am really not sure if that is correct.
I would be very thankful for any tips or hints..
best regards
Lukas
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