R help - Mar 2010 - Analogue to SPSS regression commands ENTER and REMOVE in R?

I am not sure if this question has been asked before - but is there a
procedure in R (in lm or glm?) that is equivalent to ENTER and REMOVE
regression commands in SPSS?
Thanks a lot!

-- 
Dimitri Liakhovitski
Ninah.com
Dimitri.Liakhovitski at ninah.com

Hi Dimitri,
It works a bit differently:

## The SPSS way:
compute dum1 = 0.
compute dum2 = 0.
if(grp = "b") dum1 = 1.
if(grp = "c") dum2 = 1.
exe.

regression
  /var = y x1 x2 z1 z2 grp
  /des = def
  /sta = def zpp cha tol f
  /dep = y
  /met = enter x1 x2
  /met = enter z1 z2
  /met = enter dum1 dum2.

## The R way:
contrasts(Dat$grp) <- contr.treatment(n=3, base=1)

m.x <- lm(y ~ x1 + x2, data=Dat)
m.xz <- update(m.x, . ~ . + z1 + z2)
m.xzg <- update(m.xz, . ~ . + grp)
anova(m.x, m.xz, m.xzg)

Hope it helps,
Ista

On Thu, Mar 4, 2010 at 10:47 AM, Dimitri Liakhovitski <ld7631 at
gmail.com> wrote:
> I am not sure if this question has been asked before - but is there a
> procedure in R (in lm or glm?) that is equivalent to ENTER and REMOVE
> regression commands in SPSS?
> Thanks a lot!
>
> --
> Dimitri Liakhovitski
> Ninah.com
> Dimitri.Liakhovitski at ninah.com
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Ista Zahn
Graduate student
University of Rochester
Department of Clinical and Social Psychology
http://yourpsyche.org

I bet you stirred the pot here because you arre asking  about stepwise
procedures.  Look at step, or stepAIC in the MASS library.

\Mike


On Thu, 4 Mar 2010 07:47:34 -0800
Dimitri Liakhovitski <ld7631 at gmail.com> wrote:
> I am not sure if this question has been asked before - but is there a
> procedure in R (in lm or glm?) that is equivalent to ENTER and REMOVE
> regression commands in SPSS?
> Thanks a lot!
>

Oops, forgot the example data used in previous post:

set.seed(133)
Dat <- data.frame(y=rnorm(10),
                  x1=rnorm(10),
                  x2=rnorm(10),
                  z1=rnorm(10),
                  z2=rnorm(10),
                  grp = factor(c(rep("a", 3), rep("b", 4),
rep("c", 3)))
                  )

On Thu, Mar 4, 2010 at 11:14 AM, Ista Zahn <istazahn at gmail.com>
wrote:
> Hi Dimitri,
> It works a bit differently:
>
> ## The SPSS way:
> compute dum1 = 0.
> compute dum2 = 0.
> if(grp = "b") dum1 = 1.
> if(grp = "c") dum2 = 1.
> exe.
>
> regression
> ?/var = y x1 x2 z1 z2 grp
> ?/des = def
> ?/sta = def zpp cha tol f
> ?/dep = y
> ?/met = enter x1 x2
> ?/met = enter z1 z2
> ?/met = enter dum1 dum2.
>
> ## The R way:
> contrasts(Dat$grp) <- contr.treatment(n=3, base=1)
>
> m.x <- lm(y ~ x1 + x2, data=Dat)
> m.xz <- update(m.x, . ~ . + z1 + z2)
> m.xzg <- update(m.xz, . ~ . + grp)
> anova(m.x, m.xz, m.xzg)
>
> Hope it helps,
> Ista
>
> On Thu, Mar 4, 2010 at 10:47 AM, Dimitri Liakhovitski <ld7631 at
gmail.com> wrote:
>> I am not sure if this question has been asked before - but is there a
>> procedure in R (in lm or glm?) that is equivalent to ENTER and REMOVE
>> regression commands in SPSS?
>> Thanks a lot!
>>
>> --
>> Dimitri Liakhovitski
>> Ninah.com
>> Dimitri.Liakhovitski at ninah.com
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
>
> --
> Ista Zahn
> Graduate student
> University of Rochester
> Department of Clinical and Social Psychology
> http://yourpsyche.org
>


-- 
Ista Zahn
Graduate student
University of Rochester
Department of Clinical and Social Psychology
http://yourpsyche.org

On Mar 4, 2010, at 10:47 AM, Dimitri Liakhovitski wrote:
> I am not sure if this question has been asked before - but is there a
> procedure in R (in lm or glm?) that is equivalent to ENTER and REMOVE
> regression commands in SPSS?
> Thanks a lot!
I haven't used SPSS for 25 years (excluding a brief session where I  
talked an inexperienced SPSS user through creating a multi-way table  
of mortality ratios a couple of years ago) but my memory is that those  
operations drop or add terms to a model formula and produced  
voluminous paper output as a result. Looking at the "lm" function help
page, I guessed that I might find more information at the anova.lm  
help page and sure enough, there at the bottom of the page was  
"drop1". My vague memory that there was a matching "add1"
was rewarded
with confirmation when I followed the "drop1" link.

I generally just make another call to lm().

>
> -- 
> Dimitri Liakhovitski
> Ninah.com
> Dimitri.Liakhovitski at ninah.com
>
-- 

David Winsemius, MD
Heritage Laboratories
West Hartford, CT