Ordinal-To-Interval Scale Conversion Tables and National Items for the New Zealand Version of the WHOQOL-BREF.
The World Health Organisation Quality of Life (WHOQOL) questionnaires are widely used around the world and can claim strong cross-cultural validity due to their development in collaboration with international field centres. To enhance conceptual equivalence of quality of life across cultures, optional national items are often developed for use alongside the core instrument. The present study outlines the development of national items for the New Zealand WHOQOL-BREF. Focus groups with members of the community as well as health experts discussed what constitutes quality of life in their opinion. Based on themes extracted of aspects not contained in the existing WHOQOL instrument, 46 candidate items were generated and subsequently rated for their importance by a random sample of 585 individuals from the general population. Applying importance criteria reduced these items to 24, which were then sent to another large random sample (n = 808) to be rated alongside the existing WHOQOL-BREF. A final set of five items met the criteria for national items. Confirmatory factor analysis identified four national items as belonging to the psychological domain of quality of life, and one item to the social domain. Rasch analysis validated these results and generated ordinal-to-interval conversion algorithms to allow use of parametric statistics for domain scores with and without national items.
Auckland University of Technology, Auckland, New Zealand.
Christian U
http://orcid.org/0000-0002-7298-0736
CU
Krägeloh
Auckland University of Technology, Auckland, New Zealand.
D Rex
DR
Billington
Auckland University of Technology, Auckland, New Zealand.
Patricia Hsien-Chuan
PH
Hsu
Auckland University of Technology, Auckland, New Zealand.
Xuan Joanna
XJ
Feng
Auckland University of Technology, Auckland, New Zealand.
Oleg N
ON
Medvedev
University of Brighton, Brighton, United Kingdom.
Paula
P
Kersten
Auckland University of Technology, Auckland, New Zealand.
Jason
J
Landon
Auckland University of Technology, Auckland, New Zealand.
Richard J
RJ
Siegert
D000328:Adult; D005260:Female; D017144:Focus Groups; D006801:Humans; D008297:Male; D008875:Middle Aged; D009520:New Zealand; D011594:Psychometrics / Q000592:standards; D011788:Quality of Life; D012015:Reference Standards; D011795:Surveys and Questionnaires / Q000592:standards*; D014944:World Health Organization; D055815:Young Adult