Before revision:  We aim to investigate the cross-cultural comparability of IADL. METHODS: IADL were measured in 3,571 individuals (67.1 +- {\pm} 9.5 years old, 44.7\% female) in 11 international studies using the Amsterdam IADL Questionnaire (A-IADL-Q). Cultural, age and gender bias were assessed on item level using differential item functioning (DIF) and on scale level by calculating correlations between IADL and cognitive and functional measures . RESULTS: We did not find meaningful bias on item or on scale level, as indicated by low DIF effect sizes (  R2 range 0-0.03) and correlations in expected directions and of similar magnitude.
After revision:  We aim to investigate the cross-cultural comparability of IADL. METHODS: IADL were measured in 3,571 individuals (67.1 +- {\pm} 9.5 years old, 44.7\% female) in 11 international studies using the Amsterdam IADL Questionnaire . Item bias was assessed using differential item functioning (DIF) and on scale level by calculating correlations between IADL and cognitive and functional measures . RESULTS: We did not find meaningful bias on item or on scale level, as indicated by low DIF effect sizes ( R2 range 0-0.03) and correlations in expected directions and of similar magnitude.