forecast.lm() and NEWDATA

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
project.org] On Behalf Of Ryan
Sent: Monday, November 04, 2013 4:19 PM
To: David Winsemius
Cc: r-help at r-project.org
Subject: Re: [R] forecast.lm() and NEWDATA

Hi David (and everyone)

Thank you for your reply.

I see I copied down the code wrong for the regression. I was using the
"+" seperator, and not ",".  The regression was working.

I made a mistake with the NEWDATA, where I also used "+", instead of
",", however I see both work but return very different results. I have
corrected the mistake.

However, I am still receiving the same error when I try to run the
forecast.lm.
"

forecast.lm(REGGY, h=5)

i receive the following error
"Error in as.data.frame(newdata) :
  argument "newdata" is missing, with no default""

I am sorry to say, I don't understand your reference to the string
output when you mentioned

"

You should post the output of str() on the data-objects that has the 12
variables and if it was modified the data argument pasted to `lm()`
when you made REGGY.

"
  As of right now, NEWDATA includes all the independent variables from
the REGGY Regression.


Should the NEWDATA data.frame include the dependent variable?

Also, is it necessary to reformat all variables as time series? (I have
not currently done so)

Regards
Ryan

On 2013-11-01 07:28 PM, David Winsemius wrote:

On Nov 1, 2013, at 6:50 AM, Ryan wrote:

Good day all.

I am hoping you can help me (and I did this right). I've been

working in R for a week now, and have encountered a problem with
forecast.lm().

I have a list of 12 variables, all type = double, with 15 data

entries.

(I imported them from tab delimited text files, and then formatted

as.numeric to change from list to double)

(I understand that this leaves me rather limited in my degrees of

freedom, but working with what I have, sadly. )

I have a LM model, such that
REGGY = lm(formula=Y~A,B,C,...,I,J)

This looks wrong. Separating independent predictors with commas would

be highly unusual.

which I am happy with.

I have
NEWDATA = data.frame(A+B+C+D....+I+J)

This also looks wrong. Separating arguments to data.frame with "+"-

signs is surely wrong.

When i try to run

forecast.lm(REGGY, h=5)

i receive the following error
"Error in as.data.frame(newdata) :
  argument "newdata" is missing, with no default"

If your code prior to calling forecast on the REGGY-object was really

what you showed here, I am not surprised. You should post the output of
str() on the data-objects that has the 12 variables and if it was
modified the data argument pasted to `lm()` when you made REGGY.
(Beginners should name their data arguments.)

When I run
forecast.lm(REGGY, NEWDATA, h=5)
I receive the confidence intervals of the 15 data entries I already

possess. I understand that by including NEWDATA, the "h=5" is ignored,
but without NEWDATA, I receive the error message.

Can anyone help me please?

Regards
Ryan

P.S The forecast is trying to predict the next 5 values for Y from

the regression model pasted above. I'm a bit rusty with regressions,
but I think I've covered my bases as well as I can, and from what I
understand of the R code, I'm following the right steps.

Not if what you posted here was your code. I think you missed a few

crucials points about R syntax.