## Not run:
# #############################################################################
# # EXAMPLE 1: Nested logit model multiple choice dataset data.si06
# #############################################################################
#
# data(data.si06)
# dat <- data.si06
#
# #** estimate 2PL nested logit model
# library(mirt)
# mod1 <- mirt::mirt( dat , model=1 , itemtype="2PLNRM" , key=rep(0,ncol(dat) ) ,
# verbose=TRUE )
# summary(mod1)
# cmod1 <- mirt.wrapper.coef(mod1)$coef
# cmod1[,-1] <- round( cmod1[,-1] , 3)
#
# #** normalize item parameters according Suh and Bolt (2010)
# cmod2 <- cmod1
#
# # slope parameters
# ind <- grep("ak",colnames(cmod2))
# h1 <- cmod2[ ,ind ]
# cmod2[,ind] <- t( apply( h1 , 1 , FUN = function(ll){ ll - mean(ll) } ) )
# # item intercepts
# ind <- paste0( "d" , 0:9 )
# ind <- which( colnames(cmod2) %in% ind )
# h1 <- cmod2[ ,ind ]
# cmod2[,ind] <- t( apply( h1 , 1 , FUN = function(ll){ ll - mean(ll) } ) )
# cmod2[,-1] <- round( cmod2[,-1] , 3)
# ## End(Not run)
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