Investigating an Invariant Item Ordering for Polytomously Scored Items

Abstract

Investigating an invariant item ordering for polytomously scored itemsLigtvoet, R.; van der Ark, L.A.; Te Marvelde, J.M.; Sijtsma, K. General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.-Users may download and print one copy of any publication from the public portal for the purpose of private study or research -You may not further distribute the material or use it for any profit-making activity or commercial gain -You may freely distribute the URL identifying the publication in the public portal Take down policy If you believe that this document breaches copyright, please contact us providing details, and we will remove access to the work immediately and investigate your claim.

A hierarchy of distress and invariant item ordering in the General Health Questionnaire-12

“…IIO is not demonstrated when several items tap the same level of the latent trait (Ligtvoet et al, 2010;Watson et al, in press). This suggests that several of the items of the GHQ-12 assess the same level of the latent trait of distress, and this is supported by the fact that the mean score for five of these items was between 2.02-2.07.…”

“…Although these studies suggest a hierarchy of emotions, it is possible that the ordering of items varies across samples, thus indicating that these scales are not true hierarchies, and rendering them less valuable (Ligtvoet et al, 2010).…”

“…IIO is therefore crucial for establishing a scale hierarchy that is replicable across samples, and would provide powerful evidence for the utility and generalisation of such scales. Recently, a method for investigating IIO has been developed (Ligtvoet et al, 2010), and behavioural scales (e.g. physical function, feeding) have been found that demonstrate IIO (Watson et al, in press).…”

Polytomous Latent Scales for the Investigation of the Ordering of Items

“…Ligtvoet, Van der Ark, Te Marvelde, and Sijtsma (2010a) proposed a method for dealing with multiple results when testing the MIIO property. Here, we adapt this method to the MS-CPM and IT properties, but first we explain the MIIO method (see Ligtvoet et al, 2010a, for details).…”

“…If MIIO does not hold for each of the 1 2 × k × (k − 1) item pairs, items are removed oneby-one until a subset remains for which MIIO holds (Ligtvoet et al, 2010a). A backward itemselection procedure reaches this goal while removing as few items as possible.…”