% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/aiken_v.R
\name{aiken_v}
\alias{aiken_v}
\title{Aiken's V coefficient of content validity}
\usage{
aiken_v(ratings, lo = 1, hi = 4, na.rm = FALSE)
}
\arguments{
\item{ratings}{A numeric matrix or data frame of expert ratings (rows =
experts, columns = items). A numeric vector is also accepted, treated
as a single item.}

\item{lo}{Numeric. Minimum possible rating on the scale. Default 1.}

\item{hi}{Numeric. Maximum possible rating on the scale. Default 4.}

\item{na.rm}{Logical. If \code{TRUE}, missing ratings are excluded.
Defaults to \code{FALSE}.}
}
\value{
A named numeric vector of V values, one per item. If \code{ratings}
is a vector, returns a single numeric value.
}
\description{
Computes Aiken's V (Aiken, 1985), an index of content validity that uses
the full rating scale rather than dichotomizing responses as in I-CVI.
Aiken's V ranges from 0 to 1, where 1 indicates all experts gave the
maximum rating and 0 indicates all gave the minimum.
}
\details{
Aiken's V is calculated as:

\deqn{V = (\bar{X} - lo) / (hi - lo)}

where \eqn{\bar{X}} is the mean expert rating across raters, and \code{lo} and
\code{hi} are the minimum and maximum possible scale values, respectively.

A common cutoff is V >= 0.70 for adequate content validity, though
stricter thresholds are sometimes applied depending on panel size and
research context. Unlike I-CVI, Aiken's V uses the full rating scale, so
a rating of 4 contributes more than a rating of 3 (rather than both being
counted equally as "relevant").
}
\examples{
ratings <- matrix(
  c(4, 4, 3, 4, 4,
    3, 4, 4, 4, 3,
    2, 3, 3, 4, 3,
    1, 2, 3, 2, 3),
  nrow = 5,
  dimnames = list(NULL, paste0("item", 1:4))
)
aiken_v(ratings)

# 5-point scale
aiken_v(c(5, 4, 5, 5, 4), lo = 1, hi = 5)

}
\references{
Aiken, L. R. (1985). Three coefficients for analyzing the reliability and
validity of ratings. \emph{Educational and Psychological Measurement}, 45(1),
131-142. \doi{10.1177/0013164485451012}
}
\seealso{
\code{\link[=icvi]{icvi()}}
}
