[R] Intercept=0 in gam from gam package

2009-09-10 Thread Corrado
Dear R list,

is it possible to force the intercept to assume the value of 0 (that is no 
intercept) in gam from gam package?

Regards
-- 
Corrado Topi

Global Climate Change  Biodiversity Indicators
Area 18,Department of Biology
University of York, York, YO10 5YW, UK
Phone: + 44 (0) 1904 328645, E-mail: ct...@york.ac.uk

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Re: [R] Intercept=0 in gam from gam package

2009-09-10 Thread Gavin Simpson
On Thu, 2009-09-10 at 14:58 +0100, Corrado wrote:
 Dear R list,
 
 is it possible to force the intercept to assume the value of 0 (that is no 
 intercept) in gam from gam package?

Just like you would in lm or glm for example, by adding -1 to your
formula. ?gam suggests you look at ?lm to see about the formulas for
example.

data(airquality)
mod0 - gam(Ozone^(1/3) ~ lo(Solar.R) + lo(Wind, Temp) - 1, 
data = airquality, na = na.gam.replace)
mod1 - gam(Ozone^(1/3) ~ lo(Solar.R) + lo(Wind, Temp), 
data = airquality, na = na.gam.replace)

summary(mod0)
summary(mod1)

HTH

G

 
 Regards
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