[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

st: btscs, cubic splines and predicting meaningful values

From   "Lukas Kasten" <[email protected]>
To   <[email protected]>
Subject   st: btscs, cubic splines and predicting meaningful values
Date   Thu, 21 Jan 2010 16:58:41 +0100

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
*   For searches and help try:

© Copyright 1996–2024 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index