Differential item functioning of the CESDR-R and GAD-7 in African and white working adults

Orientation: Depression and anxiety can have undesirable consequences for employees and their employers. It is therefore important that employers pay attention to the existence and extent of depression and anxiety. However, measuring these constructs requires unbiased, reliable and valid instruments.Research purpose: To facilitate unbiased measurement of depression and anxiety, we investigated differential item functioning of the Centre for Epidemiologic Studies Depression Scale-Revised (CESD-R) and Generalised Anxiety Disorder Scale 7 (GAD-7) in a sample of non-clinical African and white working adults.Motivation for the study: Biased measurement instruments can lead to serious problems when comparing scores between groups, using raw score cut-offs, or creating norm scores. Practitioners are legally and ethically required to ensure that any instrument used is unbiased.Research approach/design and method: A cross-sectional survey design was used. The CESD-R and GAD-7 were administered to working adults. A final sample of 551 CESD-R responses and 529 GAD-7 responses were included in the analyses. Ordinal logistic regression was performed to investigate differential item functioning.Main findings: Both CESD-R and GAD-7 showed some evidence of differential item functioning although it was mostly small in magnitude. Item bias had some minor non-negligible impact on aggregated observed scores within specific ranges of the underlying traits.Practical/managerial implications: Both CESD-R and GAD-7 show promise as instruments that can be utilised to explore the experience of anxiety and depression in African and white employees.Contribution/value-add: This study is a promising first step towards the measurement fairness of the CESD-R and GAD-7 in the South African context.