Having parents complete questionnaires about their multilingual children’s language experience can be time-consuming. Asking more questions, we often think, will lead to better information, but does it? That’s exactly what we wanted to find out in this paper.

🔎What did we do?

▪️We collected language proficiency data from a diverse group of bi- and trilingual children aged 5 to 9 years old who were growing up in France, the Netherlands or the UK.
▪️We had parents complete the Q-BEx questionnaire and then compared alternative measures of language exposure as predictors of language proficiency.
▪️We identified the optimal ones using information-theoretic and cross-validation methods.

🔎What did we find?

▪️Cumulative exposure (how much children hear a language over time) yields the most reliable predictor of proficiency in the societal language.
▪️Current exposure in the home yields the optimal predictor of proficiency in the heritage language.
▪️The greatest level of questionnaire detail did not yield more informative predictors.

The upshot? If you’re interested in predicting multilingual children’s language proficiency based on their language experience, these two components of the Q-BEx Language Exposure and Use module are sufficient: Current Estimates (short) and Cumulative Estimates.

Want to know more? De Cat, C., Gusnanto, A., Kašćelan, D., Prévost, P., Serratrice, L., Tuller, L., & Unsworth, S. (2025). How detailed do measures of bilingual language experience need to be? A cost–benefit analysis using the Q-BEx questionnaire. Bilingualism: Language and Cognition, 1–12. https://doi.org/10.1017/S1366728925100497