R help - Jul 2004 - formula and lm

Hi, don' t understand why the function fomula have this error, i enclose
the parameter "a" with the function I()
Thank Ruben
 x<-1:5
y<-c(  2  ,4 , 6 , 8 ,11)
formu<-y~I(a*x)
form<-formula(formu)
dummy<-data.frame(x=x,y=y)
fm<-lm(form,data=dummy)
Error in unique(c("AsIs", oldClass(x))) : Object "a" not
found

It wants to compute a*x given a and x, and then use ordinarly least 
squares to estimate b0 and b1 in y = b0 + b1*I(a*x).  If that is what 
you intend, you must supply a.  If you want to estimate a, e.g., with no 
constant, use   y~x-1.  Does this answer the question?  hope this 
helps.  spencer graves

solares at unsl.edu.ar wrote:
>Hi, don' t understand why the function fomula have this error, i enclose
>the parameter "a" with the function I()
>Thank Ruben
> x<-1:5
>y<-c(  2  ,4 , 6 , 8 ,11)
>formu<-y~I(a*x)
>form<-formula(formu)
>dummy<-data.frame(x=x,y=y)
>fm<-lm(form,data=dummy)
>Error in unique(c("AsIs", oldClass(x))) : Object "a" not
found
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
>https://www.stat.math.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>  
>

Hallo

On 15 Jul 2004 at 13:46, solares at unsl.edu.ar wrote:
> Hi, don' t understand why the function fomula have this error, i
> enclose the parameter "a" with the function I() Thank Ruben
>  x<-1:5
> y<-c(  2  ,4 , 6 , 8 ,11)
> formu<-y~I(a*x)
> form<-formula(formu)
> dummy<-data.frame(x=x,y=y)
> fm<-lm(form,data=dummy)
> Error in unique(c("AsIs", oldClass(x))) : Object "a"
not found
You did not created object "a" before you have done your 
calculations, as the error message clearly states. 

try

a<-5
x<-1:5
y<-c(  2  ,4 , 6 , 8 ,11)
formu<-y~I(a*x)
form<-formula(formu)
dummy<-data.frame(x=x,y=y)
fm<-lm(form,data=dummy)

But if you want to estimate "a" follow previous replies and try to 
read help page for lm(). 

formu<-y~x

is probably what you want :-).

Cheers
Petr
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
Petr Pikal
petr.pikal at precheza.cz