[EMAIL PROTECTED] wrote:

I am trying to do power calculations for the proportional odds model using the asypow 
library.

The code

noncenta90b10<-asypow.noncent(theta.ha=a9010,info.mat=infomatrixa90b10,constraints=constrt)

returns

Error in max(..., na.rm = na.rm) : invalid "mode" of argument.

the various arguments I've used are:
a9010
          [,1]
[1,] -1.7357568
[2,] -0.1928619
specifying the theta.ha array as a row not a column makes no difference




infomatrixa90b10


[,1] [,2]
[1,] 0.967005807 -0.004699262
[2,] -0.004699262 0.903852346


constrt


[,1] [,2] [,3] [1,] "1" "a" "-1.92861865194525"
[2,] "1" "b" "0"



I'm probably missing something very simple, but I can't see what it is. Can anyone help?



Problem is with your constarint matrix. From the help file (which admittedlt could be clearer)
constrain is a 3-column matrix. First element in a row should be 1 to indicate a param set == to a value,
2 to indicate equality of two params. You put 1, so we assume first case. Second row element should be , in this case,
index of param set to value, and cannot be "a" or "b". Lets suppose yours are first and second parameter, then it shoud be 1 and 2, respectively.
Finally, in this case, third row element should be value.


So you should use something like
constrt <- matrix( c(1,1,-1.9286, 1,2,0), 2, 3, byrow=TRUE)

and then, using your values for the other arguments,

> asypow.noncent(a9010, infomatrix, constrt)
$w
          [,1]
[1,] 0.06993048

$df
[1] 2

Kjetil


--

Kjetil Halvorsen.

Peace is the most effective weapon of mass construction.
              --  Mahdi Elmandjra

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