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Investigating invariant item ordering in the Mental Health Inventory : an illustration of the use of different methods

Watson, Roger; Wang, Wenru; Thompson, David R.; Meijer, Rob R.


Wenru Wang

David R. Thompson

Rob R. Meijer


Invariant item ordering is a property of scales whereby the items are scored in the same order across a wide range of the latent trait and across a wide range of respondents. In the package ‘mokken’ in the statistical software R, the ability to analyse Mokken scales for invariant item ordering has recently been available and techniques for inspecting visually the item response curves of item pairs, have also been included. While methods to assess invariant item ordering are available, there have been indications that items representing extremes of distress in mental well-being scales, such as suicidal ideation, may lead to claiming invariant item ordering where it does not exist. We used the Mental Health Inventory to see if invariant item ordering was indicated in any Mokken scales derived and to see if this was being influenced by extreme items. A Mokken scale was derived indicating invariant item ordering. Visual inspection of the item pairs indicated that the most difficult item (suicidal ideation) was located far from the remaining cluster of items. Removing this item lowered invariant item ordering to an unacceptable level.


Watson, R., Wang, W., Thompson, D. R., & Meijer, R. R. (2014). Investigating invariant item ordering in the Mental Health Inventory : an illustration of the use of different methods. Personality and individual differences, 66(August), 74-78.

Journal Article Type Article
Acceptance Date Mar 15, 2014
Online Publication Date Apr 12, 2014
Publication Date 2014-08
Deposit Date Apr 10, 2015
Publicly Available Date Apr 10, 2015
Journal Personality and individual differences
Print ISSN 0191-8869
Electronic ISSN 0191-8869
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 66
Issue August
Pages 74-78
Keywords Item response theory, Mokken scaling, Invariant item ordering, Mental health, Coronary heart disease
Public URL
Publisher URL
Additional Information Author's accepted manuscript of article published in: Personality and individual differences, 2014, v.66.


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