Thinking-aloud methodology applied to health questionnaire development and validation: a scoping review

The development of valid and reliable health questionnaires relies on respondents' accurate comprehension of items. The thinking-aloud (TA) technique, where participants verbalize their thought processes while answering survey questions, offers a powerful means to explore cognitive mechanisms underlying response behaviour. Despite its wide use, there is no consensus on how TA protocols should be designed, conducted, and analysed.

This scoping review aimed to map methodological approaches applied to TA in health-related questionnaire development and validation, describe their variability, and critically examine current methodological practices to inform future research.

PubMed, Scopus, and Embase were searched on July 17, 2025, without time limits. Eligible studies were original articles in English applying TA for questionnaire validation, including assessment of content, face, construct validity, or comprehensibility. Two reviewers independently screened records and extracted data using a standardized charting form. An operational criterion was used to judge the completeness of methodological reporting. Data were synthesized narratively and tabulated to describe study purposes, TA typologies, analytical strategies, and theoretical frameworks.

From 1,678 retrieved records, 210 studies met inclusion criteria, of which 84 provided complete methodological descriptions. Most of the 84 studies involved patients (48%) and used concurrent TA (48%), with frequent prompting (55%) and probing (48%). Sessions were mainly face-to-face (71%), audio recorded (64%), and transcribed verbatim. Thematic (38%) and content (26%) analyses predominated, often supported by NVivo. The Survey Response Model was the most cited theoretical framework (26%), though 22% of studies lacked any theoretical reference. Coding strategies were mixed (36%), and about half of the studies reported questionnaire revisions after analysis.

TA remains a versatile but methodologically fragmented approach in questionnaire validation. The lack of standardization limits comparability and interpretability across studies. Greater transparency in reporting and explicit theoretical framing are recommended to improve methodological rigor.

The review followed the PRISMA-ScR framework and was prospectively registered on OSF (DOI: https://doi.org/10.17605/OSF.IO/AZY3).