Editing Likert scale (section)

=== Latent variable models ===

A common practice for analyzing responses to collections of Likert scale items is to summarize them via a [[latent variable model]], for example using [[factor analysis]] or [[item response theory]].

==== Rasch model ====

Likert scale data can, in principle, be used as a basis for obtaining interval level estimates on a continuum by applying the [[polytomous Rasch model]], when data can be obtained that fit this model. In addition, the polytomous Rasch model permits testing of the [[hypothesis]] that the statements reflect increasing levels of an attitude or trait, as intended. For example, application of the model often indicates that the neutral category does not represent a level of attitude or trait between the disagree and agree categories.

Not every set of Likert scaled items can be used for Rasch measurement. The data has to be thoroughly checked to fulfill the strict formal [[axiom]]s of the model. However, the raw scores are the [[sufficient statistics]] for the Rasch measures, a deliberate choice by [[Georg Rasch]], so, if you are prepared to accept the raw scores as valid, then you can also accept the Rasch measures as valid.