subscales function

Function to create subscales based on a design matrix

This convenience function is provided to facilitate extracting subscales from a single set of item responses.

subscales(items, scales, scale.names = NA, score.items = FALSE,
          check.reliability = FALSE, key=NA)

Arguments

• items: The item response (scored or not)
• scales: A design matrix, with items represented in rows and separate subscales represented in columns. An item may appear in more than one subscale.
• scale.names: Optional vector of names for the subscales
• score.items: If responses are not scored, they may be scored using score.items=TRUE (key must be provided)
• check.reliability: If check.reliability=TRUE, the reliability for each subscale will be calculted
• key: Optional key, required only if score.scales=TRUE.

Details

This function provides an easy way to create new datasets from a single set of item responses. This function is also a front end for score and reliability, enabling the item responses to be partitioned into separate scales, scored, and reliability analyses performed using this one function.

Returns

A list is returned. Results for each subscale (i.e., column in the scales matrix) are provided as sparate objects in that list. - score: Each examinee's score on the associated subscale

• reliablity: Reliability results (if requested) for the associated subscale

• scored: The scored item responses (if required) for each respondent for the associated subscale

Author(s)

John Willse, Zhan Shu

See Also

reliability, score

Examples

# Example data included with package
data(CTTdata)
data(CTTkey)

# design matrix
q <- matrix(c(1,0,
              1,0,
              1,0,
              1,0,
              1,0,
              1,0,
              1,0,
              1,0,
              1,0,
              1,1,
              0,1,
              0,1,
              0,1,
              0,1,
              0,1,
              0,1,
              0,1,
              0,1,
              0,1,
              0,1), ncol=2, byrow=TRUE)
subscales(CTTdata,q,c("T1","T2"),TRUE,TRUE,CTTkey)