If I understand correctly the result you are trying to achieve, I think
what you may be looking for is this:
model1.coeff <- lm(dv ~ iv1 + iv2 + iv3, data =
merged.dataset[merged.dataset$model1 == 1, ])
This will give you a regression using only the data for which model1 == 1.
on 08/22/2008 11:07 AM jim holtman said the following:
Exactly what do you want this statement to do:
if(merged.dataset$model1 == 1) model1.coeff <- lm(dv ~ iv1 + iv2 +
iv3, data = merged.dataset)
The result in the "if" is a vector of logical values (assuming that
merged.dataset is longer than 1); that is the source of the error
message. Do you want the regression to be done on every row? So what
is the problem you are trying to solve?
On Fri, Aug 22, 2008 at 10:47 AM, Kate Rohrbaugh
<[EMAIL PROTECTED]> wrote:
Greetings,
Apologies for such a simple question, but I have been trying to figure this out for a few
days now (I'm quite new to R), have read manuals, list posts, etc., and not finding
precisely what I need. I am accustomed to working in Stata, but I am currently working
through the multilevel package right now. In Stata, I would include the statement
"if model1 == 1" at the end of my regression statement, but I can't seem to
find the correct syntax for doing the same thing in R.
I have successfully converted Stata datasets, merged, aggregated, run lm, etc.,
but this simple task is evading me entirely.
Here's what I have tried (and various iterations):
if(merged.dataset$model1 == 1) model1.coeff <- lm(dv ~ iv1 + iv2 + iv3, data =
merged.dataset)
I get this:
Warning message:
In if (merged.dataset$model1 == 1) model1.coeff <- lm(dv ~ iv + :
the condition has length > 1 and only the first element will be used
What it seems to do is just run lm on the first opportunities of model1==1, but
then doesn't try it again. I tried sorting so that the model1==1 appear first,
but that doesn't seem to be a great solution either.
I'll just go back into Stata and create separate new datasets if I have to, but
there HAS to be a more elegant way.
Thank you for ANY feedback!
Kate
Kate Rohrbaugh
Independent Project Analysis, Inc.
44426 Atwater Drive
Ashburn, VA 20147
office - 703.726.5465
fax - 703.729.8301
email - [EMAIL PROTECTED]
website - www.ipaglobal.com
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