[S] difference between predict

alain Le Tertre (alain@worldnet.fr)
Wed, 29 Jul 1998 10:24:04 +0200


In S-plus 4 guide to statistics p 221, "Specifying type="terms" allows you
to compute the component of the prediction for each term separately. Summing
the columns of the matrix and adding the constant (intercept) term is
equivalent to specifying type="link"".
So try :
zzz_gam(Kyphosis ~ poly(Age, 2) + s(Start), data = kyphosis)
cbind(predict(zzz,type="link"),zzz$coef[1]+rowSums(predict(zzz,type="terms")
))
give you :
1 1.6582944 2.059893
2 1.1161389 1.517737
3 1.6671144 2.068713
4 1.1938420 1.595441
5 0.8517588 1.253357
6 0.8213737 1.222972
7 1.0687632 1.470362
8 1.0036325 1.405231
9 1.1289169 1.530515
10 1.2703754 1.671974
11 1.1993687 1.600967
[snip]
Did i misunderstand something?

I'm using S-plus 4.0 release 3 on w95.

O__ ---- Alain Le Tertre
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email: alain@worldnet.fr

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