Explaining differential item functioning focusing on the crucial role of external information - an example from the measurement of adolescent mental health.
Adolescent
Adolescent Behavior
/ psychology
Adolescent Health
/ statistics & numerical data
Algorithms
Child
Female
Health Surveys
/ methods
Humans
Male
Mental Health
/ statistics & numerical data
Psychometrics
/ methods
Reproducibility of Results
Sex Factors
Students
/ statistics & numerical data
Sweden
Differential item functioning (DIF)
Psychosomatic problems
Rasch model
Resolving for DIF
Source of DIF
Validity and reliability, HBSC
Journal
BMC medical research methodology
ISSN: 1471-2288
Titre abrégé: BMC Med Res Methodol
Pays: England
ID NLM: 100968545
Informations de publication
Date de publication:
05 09 2019
05 09 2019
Historique:
received:
01
04
2019
accepted:
26
08
2019
entrez:
7
9
2019
pubmed:
7
9
2019
medline:
4
8
2020
Statut:
epublish
Résumé
An overarching objective in research comparing different sample groups is to ensure that the reported differences in outcomes are not affected by differences between groups in the functioning of the measurement instruments, i.e. the items have to work in the same way for the different sample groups to be compared. Lack of invariance across sample groups are commonly called Differential Item Functioning (DIF). There is a sense in which the DIF of an item can be taken account of by resolving (splitting) the item into group specific items, rather than deleting the item. Resolving improves fit, retains the reliability and content provided by the item, and compensates for the DIF in estimation of person parameters on the scale of the instrument. However, it destroys invariance of the item's parameter value among the groups. Whether or not a DIF item should be resolved depends on whether the source of the DIF is relevant or irrelevant for the content of the variable. The present paper shows how external information can be used to investigate if the gender DIF found in the item "Stomach ache" in a psychosomatic symptoms scale used among adolescents may reflect abdominal pain because of a biological factor, the girls' menstrual periods. Swedish data from the international Health Behaviour in School-aged Children study (HBSC) collected in 2005/06, 2009/10 and 2013/14 were used, comprising a total of 18,983 students in grades 5, 7 and 9. A composite measure of eight items of psychosomatic problems was analysed for DIF with respect to gender and menstrual periods using the Rasch model. The results support the hypothesis that the source of the gender DIF for the item "Stomach ache" is a gender specific biological factor. In that case the DIF should be resolved if the psychosomatic measure is not intended to tap information about abdominal pain caused by a gender specific biological factor. In contrast, if the measure is intended to tap such information, the DIF should not be resolved. The conceptualisation of the measure governs whether the item showing DIF should be resolved or not.
Sections du résumé
BACKGROUND
An overarching objective in research comparing different sample groups is to ensure that the reported differences in outcomes are not affected by differences between groups in the functioning of the measurement instruments, i.e. the items have to work in the same way for the different sample groups to be compared. Lack of invariance across sample groups are commonly called Differential Item Functioning (DIF). There is a sense in which the DIF of an item can be taken account of by resolving (splitting) the item into group specific items, rather than deleting the item. Resolving improves fit, retains the reliability and content provided by the item, and compensates for the DIF in estimation of person parameters on the scale of the instrument. However, it destroys invariance of the item's parameter value among the groups. Whether or not a DIF item should be resolved depends on whether the source of the DIF is relevant or irrelevant for the content of the variable. The present paper shows how external information can be used to investigate if the gender DIF found in the item "Stomach ache" in a psychosomatic symptoms scale used among adolescents may reflect abdominal pain because of a biological factor, the girls' menstrual periods.
METHODS
Swedish data from the international Health Behaviour in School-aged Children study (HBSC) collected in 2005/06, 2009/10 and 2013/14 were used, comprising a total of 18,983 students in grades 5, 7 and 9. A composite measure of eight items of psychosomatic problems was analysed for DIF with respect to gender and menstrual periods using the Rasch model.
RESULTS
The results support the hypothesis that the source of the gender DIF for the item "Stomach ache" is a gender specific biological factor. In that case the DIF should be resolved if the psychosomatic measure is not intended to tap information about abdominal pain caused by a gender specific biological factor. In contrast, if the measure is intended to tap such information, the DIF should not be resolved.
CONCLUSIONS
The conceptualisation of the measure governs whether the item showing DIF should be resolved or not.
Identifiants
pubmed: 31488055
doi: 10.1186/s12874-019-0828-3
pii: 10.1186/s12874-019-0828-3
pmc: PMC6729037
doi:
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
185Références
Int J Epidemiol. 1998 Dec;27(6):935
pubmed: 10024183
Qual Life Res. 2014 Dec;23(10):2883-8
pubmed: 24848597
Eur Child Adolesc Psychiatry. 2015 Jun;24(6):685-94
pubmed: 25537263
Eur J Public Health. 2015 Apr;25 Suppl 2:83-9
pubmed: 25805796
Health Qual Life Outcomes. 2017 Sep 19;15(1):181
pubmed: 28927468
Educ Psychol Meas. 2015 Apr;75(2):185-207
pubmed: 29795818