, why 2nd one is
called centred dummy? Why people prefer for it, not the Standard dummy
definition (i.e. dummy1).
Can you please explain?
Thanks and regards,
-Original Message-
From: Gabor Grothendieck [mailto:ggrothendi...@gmail.com]
Sent: 12 January 2011 05:47
To: Christofer Bogaso
Cc: r-help
Christofer,
I am not sure I understand how you are using your dummy variables. Generally if
you have n categories you need n-1 dummy variables. Thus if you have three
categories, low, medium, high and want to compare two of the levels to a
reference level (a coding scheme sometimes called refere
On Tue, Jan 11, 2011 at 3:18 PM, Christofer Bogaso
wrote:
> Dear all, I would like to ask one question related to statistics, for
> specifically on defining dummy variables. As of now, I have come across 3
> different kind of dummy variables (assuming I am working with Seasonal
> dummy, and number
You are not offering example of real codings but are rather showing
something1 that you think looks like something2 (in R) that looks like
something3 (in a textbook?). My guess is that the something2 might be
contrast matrices or model matrices.
If you want a contrast matrix whose columns s
R does not use dummy variables. Models and contrasts are specified in
more natural, model formula based ways. See
?arima
and/or CRAN's Time Series task view for numerous packages that fit time series.
-- Bert
On Tue, Jan 11, 2011 at 12:18 PM, Christofer Bogaso
wrote:
> Dear all, I would like
Dear all, I would like to ask one question related to statistics, for
specifically on defining dummy variables. As of now, I have come across 3
different kind of dummy variables (assuming I am working with Seasonal
dummy, and number of season is 4):
> dummy1 <- diag(4)
> for(i in 1:3) dummy1 <- rb
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