Purpose: This study explored approaches for measuring vocabulary among bilingual children with varying levels of proficiency in Spanish and English.
Method: One hundred fifteen kindergarten and first-grade Spanish-English-speaking children completed measures of vocabulary and sentence repetition in Spanish and English. Scores were derived from their responses to the vocabulary measure: Spanish-only vocabulary, English-only vocabulary, conceptual vocabulary, and total vocabulary. Best language sentence repetition was also obtained. Using both visualization of data and statistical analysis, we tested for potential associations between children's relative language skills in Spanish and English and the scores they received on each of the vocabulary metrics.
Results: Participants' single-language vocabulary scores were linearly associated with their relative language scores. Higher relative Spanish language skills corresponded with higher Spanish-only vocabulary scores, and higher English language skills corresponded with higher English-only vocabulary scores. A quadratic association between children's relative language and their conceptual vocabulary scores was observed. Children with more balanced skills in Spanish and English received lower scores for conceptual vocabulary. No association between total vocabulary and relative language was observed.
Conclusions: Results revealed evidence of differential test bias for single-language vocabulary scores and conceptual vocabulary scores. Spanish-only vocabulary underestimated knowledge of participants with higher English proficiency, whereas English-only vocabulary underestimated knowledge of participants with higher Spanish proficiency. Conceptual scoring yielded lower values for participants with relatively balanced proficiency in Spanish and English. There is need for further consideration of score and test functioning across the full continuum of bilinguals with dynamic proficiencies in each of their languages.
Supplemental material: https://doi.org/10.23641/asha.23796330.