From: Doran, Harold <HDoran_at_air.org>

Date: Thu 24 Aug 2006 - 22:54:24 EST

cat('theta is about', round(theta,2), ', se', 1/sqrt(-second_deriv), '\n')

}

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Thu Aug 24 23:05:39 2006

Date: Thu 24 Aug 2006 - 22:54:24 EST

For example, here is how my current function operates.

> rasch.max(c(1,1,0,0), c(-1,.5,0,1))

theta is about 0.14 , se 1.063972

I'm not quite sure how to accomplish the same thing using optim. Can anyone offer a suggestion?

rasch.max <- function(x, b_vector){

old <- updated for(k in seq(along=b_vector)) p[k] <- rasch(theta,b_vector[k]) first_deriv <- sum(x) - sum(p) second_deriv <- sum((1-p)*-p) change <- (first_deriv/second_deriv) theta <- theta - change # This is the updated theta updated <- change }

cat('theta is about', round(theta,2), ', se', 1/sqrt(-second_deriv), '\n')

}

Harold

> version

_ platform i386-pc-mingw32 arch i386 os mingw32 system i386, mingw32 status major 2 minor 3.0 year 2006 month 04 day 24 svn rev 37909 language Rversion.string Version 2.3.0 (2006-04-24)

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