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% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/walking.R
\docType{data}
\name{walking}
\alias{walking}
\title{Walking disability data}
\format{
A data frame with 890 rows on the following 5 variables:
\describe{
\item{sex}{Sex of respondent (factor)}
\item{age}{Age of respondent}
\item{YA}{Item administered in samples A and E (factor)}
\item{YB}{Item administered in samples B and E (factor)}
\item{src}{Source: Sample A, B or E (factor)}
}
}
\description{
Two items YA and YB measuring walking disability in samples A, B and E.
}
\details{
Example dataset to demonstrate imputation of two items (YA and YB). Item YA
is administered to sample A and sample E, item YB is administered to sample B
and sample E, so sample E acts as a bridge study. Imputation using a bridge
study is better than simple equating or than imputation under independence.
Item YA corresponds to the HAQ8 item, and item YB corresponds to the GAR9
items from Van Buuren et al (2005). Sample E (as well as sample B) is the
Euridiss study (n=292), sample A is the ERGOPLUS study (n=306).
See Van Buuren (2018) section 9.4 for more details on the imputation
methodology.
}
\examples{
md.pattern(walking)
micemill <- function(n) {
for (i in 1:n) {
imp <<- mice.mids(imp) # global assignment
cors <- with(imp, cor(as.numeric(YA),
as.numeric(YB),
method = "kendall"
))
tau <<- rbind(tau, unlist(cors$analyses)) # global assignment
}
}
plotit <- function() {
matplot(
x = 1:nrow(tau), y = tau,
ylab = expression(paste("Kendall's ", tau)),
xlab = "Iteration", type = "l", lwd = 1,
lty = 1:10, col = "black"
)
}
tau <- NULL
imp <- mice(walking, max = 0, m = 10, seed = 92786)
pred <- imp$pred
pred[, c("src", "age", "sex")] <- 0
imp <- mice(walking, max = 0, m = 3, seed = 92786, pred = pred)
micemill(5)
plotit()
### to get figure 9.8 van Buuren (2018) use m=10 and micemill(20)
}
\references{
van Buuren, S., Eyres, S., Tennant, A., Hopman-Rock, M. (2005).
Improving comparability of existing data by Response Conversion.
\emph{Journal of Official Statistics}, \bold{21}(1), 53-72.
Van Buuren, S. (2018).
\href{https://stefvanbuuren.name/fimd/sec-codingsystems.html#sec:impbridge}{\emph{Flexible Imputation of Missing Data. Second Edition.}}
Chapman & Hall/CRC. Boca Raton, FL.
}
\keyword{datasets}
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