ctgdist - Likert Category Distance Calculator
It is assumed that psychological distances between the
categories are equal for the measurement instruments consisted
of polytomously scored items. According to Muraki, this
assumption must be tested. In the examination process of this
assumption, the fit indexes are obtained and evaluated. This
package provides that this assumption is removed. By with this
package, the converted scale values of all items in a
measurement instrument can be calculated by estimating a
category parameter set for each item. Thus, the calculations
can be made without any need to usage of the common category
parameter set. Through this package, the psychological
distances of the items are scaled. The scaling of a category
parameter set for each item cause differentiation of score of
the categories will be got from items. Also, the total
measurement instrument score of an individual can be calculated
according to the scaling of item score categories by with this
package.This package provides that the place of individuals
related to the structure to be measured with a measurement
instrument consisted of polytomously scored items can be reveal
more accurately. In this way, it is thought that the results
obtained about individuals can be made more sensitive, and the
differences between individuals can be revealed more
accurately. On the other hand, it can be argued that more
accurate evidences can be obtained regarding the psychometric
properties of the measurement instruments.
