[R] ace withmon=0

Frank E Harrell Jr feh3k at cms.mail.virginia.edu
Thu Apr 3 13:45:05 CEST 2003

> I was wondering whether someone can help me understand the
> following behavior of the ace-function:
> When ace is called with mon-parameter set to zero, R gives the
> message "response spec can only be lin or ordered
> (default)" and returns immediately. However, according to the help
> file mon=0 requires the response transformations to be limited
> to monotonic transformations.
> For instance, the following call of the ace-function will not be
> evaluated if one gives mon=0
>      TWOPI <- 8*atan(1)
>      x <- runif(200,0,TWOPI)
>      y <- exp(sin(x)+rnorm(200)/2)
>      a <- ace(x,y, mon=0)
> Why does mon=0 not work and how should one interpret the message
> "the response spec can only be lin or ordered" ?
> Any help will be greatly appreciated,
>   Christof
> Christof Schuster
> University of Notre Dame
> Department of Psychology                       
> 103 Haggar Hall
> Notre Dame, IN 46556

I use ace and avas quite a bit and have found a few tiny bugs such as 
that one.  I reported these bugs to the R bug list about a year ago 
and await corrections.  As you said, ace does handle nonmonotonic 
transformations of Y; you just have to turn off that error message.

Frank Harrell

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