ivs2vas {IntervalQuestionStat}

Convert interval-valued responses into equivalent visual analogue scale answers through mid-point criterion

Description

This function allows to reduce each nonempty compact real interval collected as a response in a questionnaire designed with interval-valued scales to its mid-point so it can be considered as an answer from a visual analogue scale. That is, given an nonempty compact real, interval, A, this method returns its mid-point, which can be calculated as follows,

\mathrm{mid}~A=\frac{\sup + \inf A}{2}.

Usage

ivs2vas(x)

Arguments

x

Either a single interval or either a list or matrix with several intervals stored as an IntervalData object or as an IntervalList or IntervalMatrix instance.

Value

This function returns the mid-points of the given interval-valued data to be considered as visual analogue scale responses in a questionnaire stored either as a numeric object if x argument is a single interval or a list of intervals, that is, an IntervalData or IntervalList instance, or either as a data.frame object whether x is a matrix of intervals, that is, an IntervalMatrix object.

Author(s)

José García-García [e-mail]

See Also

Interval-valued responses can be also associated to their corresponding Likert-type scale's answer through the minimum \theta-distance criterion implemented in the ivs2likert() function.

Examples

## Some ivs2vas() examples

## A single interval-valued response
i <- IntervalData(3, 3.2)
ivs2vas(i)

## A list of interval-valued responses
list <- IntervalList(c(3, 8.7), c(3.2, 9))
ivs2vas(list)

## A matrix of interval-valued responses
matrix <- IntervalMatrix(matrix(c(1, 2.6, 1.5, 3, 3.8, 6, 4, 7), 2, 4))
ivs2vas(matrix)