This is actually more like a Statistics problem:
I have a dataset with two dummy variables controlling three levels. The
problem is, one level does not have many observations compared with other
two levels (a couple of data points compared with 1000+ points on other
levels). When I run the regre
Yes. Because the slopes are supposed to be the same.
Level shifts are needed to be modeled.
Moshe Olshansky-2 wrote:
>
> Do you have a reason to treat all 3 levels together and not have a
> separate regression for each level?
>
>
> --- On Tue, 1/7/08, rlearner309 <[EM
I think the covariance between dummy variables or between dummy variables and
intercept should always be zero. meaning: no sigularity problem??
rlearner309 wrote:
>
> This is actually more like a Statistics problem:
> I have a dataset with two dummy variables controlling three lev
I think it is zero, because you have lots of zeros there. It is not like
continous variables.
Thomas Lumley wrote:
>
> On Wed, 2 Jul 2008, rlearner309 wrote:
>
>>
>> I think the covariance between dummy variables or between dummy variables
>> and
>> intercep
sorry, made a stupid mistake.
I got it.
thanks a lot!
Peter Dalgaard wrote:
>
> rlearner309 wrote:
>> I think it is zero, because you have lots of zeros there. It is not like
>> continous variables.
>>
>>
> Think again. The sum of products may be zero, but t
I have a simple regression using lm().
If I just want to check the coefficient, I can use summary(lm())$coef; if I
need the standard error, I can use summary(lm())$s, if I need the residuals,
I can use summary(lm())$res. OK. How can I get the R-squares and Adjusted
R-squares using $...?
Is there
I saw this type of models in some of my company projects.
To simplify:
Y is regressed on X1 and X2. But the regression is done by two steps:
First Y is regressed on X1 with intercept, and the residuals from the first
step are used to regress on X2, without the constant. The reason to do so
i
Medicine Division of Gerontology
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>
>>>> rlearner309 <[EMAIL PROTECTED]
I have a question about how to filter the data frame:
Suppose my data frame has variables like gender, age,... How to get a subset
of the data frame, with only female (or male) and/or age > 50...? What is
the typical syntax? I tried several condition expressions, but none of them
worked...
Than
Seems that the RmySQL package does not support windows...
Thanks a lot!
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__
Thank you all!! :-)
rlearner309 wrote:
>
> I have a question about how to filter the data frame:
> Suppose my data frame has variables like gender, age,... How to get a
> subset of the data frame, with only female (or male) and/or age > 50...?
> What is the typica
Hi, I have a huge data set to deal with. Sometimes I got warning message
about limitation of memory, sometimes R reads in the data but it is very
slow.
My question is, is there anything I can do to lift the memory limitation (I
did memory.limit(4095), anything else I can do?). I know I can also
Hi,
I have a simple graph:
x <- c(1,2,3)
plot(x, pch=16,type="b")
I would like to add some notes just beside these 3 dots, and the notes are
stored in a vector:
a <- c(12,54,84)
So the result will be: there should be a "12" below the first dot (or next
to it, but not replacing the solid dot
I have a question.
I have a data set (about 100,000 observations). How would I get the
distribution curve graph? This is like, if I use hist(x, freq="TRUE",
breaks=1000) to get the histogram, now the question is, I don't need the
histogram itself, I just need the curve that connects the top of
I have a multivariate data set, and I would like to get the S-estimates of
the scatter (robust estimates of variance-covariance matrix). Which
library/function should I use?
Thank you very much!
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I know, this is a forum about R. But I am so desperate of this problem (BTW,
anyone knows any good Statistics/Math forum to post question like this?):
A and B are both n x n positive definite matrix.
Denote A > B, if A - B is positive definite.
I know this is true: if A > B, then A^{-1} < B^{-1}
How to get robust M-estimators of multivariate scatter using Huber's psi?
Which package/function should I look into? Ideally, I hope I can
self-define thresholds of Huber's psi function.
Thanks a lot!!!
--
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David Winsemius wrote:
>
> Have you looked at the obvious Task View yet?
>
> http://cran.r-project.org/web/views/Robust.html
>
>
> --
> David Winsemius
> On Nov 19, 2008, at 1:07 PM, rlearner309 wrote:
>
>>
>> How to get robust M-estimators of multiv
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