[R] how to print the full name of the factors in summary?

[John Fox]

Jen-Chien and Adaikalavan,

Weekday is specified as an ordered factor, for which the default contrast
type is contr.poly, i.e., orthogonal-polynomial contrasts. I would have
expected a 6th-degree polynomial for the 7 days of the week, and there's a
message that suggests that 3 coefficients are aliased, so there must be
redundancies among the factors. If you want contr.treatment, treating "Mon"
as the baseline level, then simply omit ordered=T from the call to factor(),
but this won't make the collinearities disappear.

I hope this helps,
 John

------------------------------
John Fox, Professor
Department of Sociology
McMaster University
Hamilton, Ontario, Canada
web: socserv.mcmaster.ca/jfox


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On
> Behalf Of Adaikalavan Ramasamy
> Sent: November-02-09 10:43 AM
> To: Jen-Chien Chang
> Cc: r-help at r-project.org
> Subject: Re: [R] how to print the full name of the factors in summary?
> 
> It would be useful to say which package the object SJ comes from or
> provide a more reproducible example.
> 
> Assuming that Demand variable is continuous and you are fitting a
> standard lm() model, then your results looks suspicious. Where are the
> coefficients for Month, Holiday, Season?
> 
> 
> 
> 
> Jen-Chien Chang wrote:
> > 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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