On Fri, Jan 23, 2009 at 4:58 PM, Gang Chen gangch...@gmail.com wrote:
With the following example using contr.sum for both factors,
dd - data.frame(a = gl(3,4), b = gl(4,1,12)) # balanced 2-way
model.matrix(~ a * b, dd, contrasts = list(a=contr.sum, b=contr.sum))
(Intercept) a1 a2 b1 b2
-help-boun...@r-project.org]
On
Behalf Of Douglas Bates
Sent: January-25-09 10:49 AM
To: Gang Chen
Cc: R-help
Subject: Re: [R] Interpreting model matrix columns when using contr.sum
On Fri, Jan 23, 2009 at 4:58 PM, Gang Chen gangch...@gmail.com wrote:
With the following example using
...@r-project.org]
On
Behalf Of Douglas Bates
Sent: January-25-09 10:49 AM
To: Gang Chen
Cc: R-help
Subject: Re: [R] Interpreting model matrix columns when using contr.sum
On Fri, Jan 23, 2009 at 4:58 PM, Gang Chen gangch...@gmail.com wrote:
With the following example using contr.sum
With the following example using contr.sum for both factors,
dd - data.frame(a = gl(3,4), b = gl(4,1,12)) # balanced 2-way
model.matrix(~ a * b, dd, contrasts = list(a=contr.sum, b=contr.sum))
(Intercept) a1 a2 b1 b2 b3 a1:b1 a2:b1 a1:b2 a2:b2 a1:b3 a2:b3
11 1 0 1 0 0
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