[R] Local linear regression: where can I find kernels?

2010-10-13 Thread Philipp Kunze
Hi there,

What I'm trying to do is to calculate the line coefficients of a local
linear regression model by hand. I'm aware that there are many great
packages out there that calculate the local expectation E(y|x) with
local linear regression, but that's not what I need. I need the
coefficients of the line that was fitted locally. So, does anybody know
of a package that gets me those coefficients? If not, I would calculate
the values by hand with a local least square fit using kernel weights
on my data. To do so, I need a function that calculates kernel weights,
i.e. K_h(x-x_i). Which function can I use?

Any help would be greatly appreciated!

Best regards,
Philipp

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[R] local linear and local constant kernel regression with np

2010-09-23 Thread Philipp Kunze
Hi there,

I ran into a weird problem using the np-package doing some local linear
kernel regression. Whenever I run the function npregbw(...) with the
option regtype=ll (local linear modelling), my optimal bandwidth is
supposed to be 1278946. This is kind of funny, because my regressor data
(189 data points) only runs from about 3.4 to about 5.9. So, what I get
as a result is a nice and straight line, the same one I would get if I
would run a normal linear regression. Whenever I set the option
regtype=lc (i.e. local constant modelling), the optimal bandwidth is
calculated as 0.795 - which sounds right to me. 

Any ideas / similar experiences?

Thanks!
Philipp

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[R] Regression using mapply?

2010-09-08 Thread Philipp Kunze
Hi,
I have huge matrices in which the response variable is in the first
column and the regressors are in the other columns. What I wanted to do
now is something like this:

#this is just to get an example-matrix
DataMatrix - rep(1,1000);
Disturbance - rnorm(900);
DataMatrix[101:1000] - DataMatrix[101:1000]+Disturbance;
DataMatrix - matrix(DataMatrix,ncol=10,nrow=100);

#estimate univariate linear model with each regressor-column, response
in the first column

for(i in 2:10){
result - lm(DataMatrix[,1]~DataMatrix[,i])
}


Is there any way to get rid of the for-loop using mapply (or some other
function)? 

Thanks!
Philipp

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