#' Moonroof
#' 
#' A data set used to build an u-charts.
#' 
#' Defect data for moonroof installation example.
#' 
#' @name moonroof
#' @docType data
#' @format A data frame with 34 observations on the following 4 variables.
#' \describe{ 
#' \item{i}{Index.} 
#' \item{yi}{The number of defects.} 
#' \item{ni}{The sample size.} 
#' \item{ui}{The proportion of defects.} }
#' @references See the source.
#' @source DeVor, R.E.; Chang, T.; Sutherland, J.W., 2007. "Statistical Quality
#' Design and Control".
#' @examples
#' 
#' data(moonroof)
#' 
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