cats2ranks: Ordered option selection to mean ranks

Description

Convert ordered option selections to mean ranks

Usage

cats2ranks(x,cats=NULL)

Arguments

A matrix or data frame of numeric values that represent ordered choices of options. Rows are considered to represent cases or respondents and columns are the data entry points, beginning with the highest ranking (usually something like "Most impo

cats

The range of numbers that represent options. The default is the vector of unique entries in x.

Value

A list with three components:
catsThe vector of options as passed or calculated.
ranksumThe sum of ranks for each option.
rankcountThe number of times each option was selected.

Details

cats2ranks converts ordered option selections to mean ranks. It is useful in the situation where a respondent is asked to select one of a number of options as the most important, another as the second most important, and so on. It counts the number of times each option code appears in each column and calculates the mean ranking of options. It is expected that there will be fewer selections available than there are options, thus creating the opportunity for biased rankings. This can occur when one or more options are not commonly chosen, but are given extreme (usually high) ranks when they are. The function calculates the mean of unallocated ranks and assigns this to all options not chosen by each respondent, correcting for this bias. cats2ranks is especially useful when respondents do not select the same number of options. The mean of unallocated ranks is calculated for each respondent so that only explicitly selected options are entered into the calculation of mean ranks.

Examples

Run this code

# first a standard 1:m option selection
 opchoice<-matrix(NA,nrow=40,ncol=5)
 for(i in 1:40) opchoice[i,]<-sample(1:10,5)
 cats2ranks(opchoice)
 # now a messy character choice with missing values
 opchoice<-matrix(NA,nrow=40,ncol=5)
 for(i in 1:40) {
  nchoices<-sample(3:5,1)
  opchoice[i,1:nchoices]<-sample(LETTERS[1:10],nchoices)
 }
 cats2ranks(opchoice)