[R] Decompose numerical factor into orthog. poly parts

[Murray Jorgensen]

Consider the following analysis of a class experiment done as a Latin Square:

> spinner <- gl(4,4,16,label=c("Murray","Angela","Shasha","Stephen"))
> order <- gl(4,1,16)
> treat <- scan()
1:  1 2 4 3
5:  4 3 1 2
9:  3 4 2 1
13:  2 1 3 4
17: 
Read 16 items
> coin <- factor(treat,label=c("5c","10c","20c","50c"))
> time <- scan()
1: 12.0 13.3 13.0 8.9
5: 9.7 7.2 7.3 8.6
9: 9.2 9.0 7.6 7.4
13: 10.1 5.7 7.5 8.9
17: 
Read 16 items
> diam <- c(19,24,28,33)
> treat
 [1] 1 2 4 3 4 3 1 2 3 4 2 1 2 1 3 4
> diam[treat]
 [1] 19 24 33 28 33 28 19 24 28 33 24 19 24 19 28 33
> d <- diam[treat]
> 
> lsmod <- lm(time ~ spinner + order + poly(d,3))
> anova(lsmod)
Analysis of Variance Table

Response: time
           Df Sum Sq Mean Sq F value   Pr(>F)   
spinner     3 39.367  13.122  9.9476 0.009594 **
order       3  7.587   2.529  1.9172 0.228001   
poly(d, 3)  3 14.208   4.736  3.5900 0.085602 . 
Residuals   6  7.915   1.319                    
---
Signif. codes:  0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1 

I'm a bit disappointed: I thought that the poly(d,3) sum of squares would
be decomposed into its three parts. How would I do that?

(Usual apologies for mental laziness.)



Dr Murray Jorgensen      http://www.stats.waikato.ac.nz/Staff/maj.html 
Department of Statistics, University of Waikato, Hamilton, New Zealand 
Email: maj at waikato.ac.nz                            Fax +64-7 838 4155
Phone  +64-7 838 4773 wk    +64 7 849 6486 home     Mobile 021 395 862

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To: r-help-request at stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._