Jack:
You are confused!
You have specified that the factor is ordered (ordered = TRUE), so you do
_not get_ the (6, not 7 btw)single degree of freedom contrasts corresponding
to weekday names. Instead you get the (default) contrasts for an ordered
factor (.L = linear, .Q = quadratic, etc.). Also you apparently do not have
all weekdays present or maybe there is partial confounding with some of your
other factors, thus producing the singularities given in the message.
While you can read up on such matters ("contrasts") in the docs and texts
about R (V&R's MASS has a nice explanation), these issues are inherently
technical. So if you do not have the requisite statistical background, I
suggest you consult a statistician.
To paraphrase an R fortune -- if you do not know how to properly use the
statistical tools, you shouldn't be using them.
Cheers,
Bert Gunter
Genentech Nonclinical Biostatistics
-----Original Message-----
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
Behalf Of Jen-Chien Chang
Sent: Monday, November 02, 2009 7:02 AM
To: r-help@r-project.org
Subject: [R] how to print the full name of the factors in summary?
Hi,
I am wondering if there is a simple way to fix the problem I am having.
For unknown reason, I could not get the full name of the factors to be
printed in the summary. I have tried to used summary.lm as well but the
problem still persists.
SJ$Weekday <-
factor(SJ$Weekday,1:7,c("Mon","Tue","Wed","Thu","Fri","Sat","Sun"),ordered=T
)
....
attach(SJ)
lm.SJ <- lm(Demand ~ Weekday+Month+Holiday+Season)
summary(lm.SJ)
Call:
lm(formula = Demand ~ Weekday + Month + Holiday + Season)
Residuals:
Min 1Q Median 3Q Max
-69.767 -12.224 -1.378 10.857 91.376
Coefficients: (3 not defined because of singularities)
Estimate Std. Error t value Pr(>|t|)
(Intercept) 88.7091 3.3442 26.527 < 2e-16 ***
Weekday.L 20.8132 2.8140 7.396 1.08e-12 ***
Weekday.Q -12.7667 2.8156 -4.534 7.99e-06 ***
Weekday.C -10.6375 2.8113 -3.784 0.000182 ***
Weekday^4 -8.3325 2.8103 -2.965 0.003238 **
---------------------------------------------
Is there a way for summary to print the full name of the factors and
levels? Say Weekday.Tue instead Weekday.L?
Thanks!
Jack Chang
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and provide commented, minimal, self-contained, reproducible code.
