EFFECT SIZE–DRIVEN SAMPLE-SIZE PLANNING, RANDOMIZATION, AND MULTISITE USE IN L2 INSTRUCTED VOCABULARY ACQUISITION EXPERIMENTAL SAMPLES

• Published in: Studies in second language acquisition Vol. 44; no. 5; pp. 1424 - 1448
• Main Authors: Vitta, Joseph P., Nicklin, Christopher, McLean, Stuart
• Format: Journal Article
• Language: English
• Published: New York, USA Cambridge University Press 01.12.2022
• Subjects: Bias; Coding; Educational Change; Effect Size; English Language Learners; Intervention; Language Acquisition; Literature Reviews; Meta Analysis; Methods Forum; Nouns; Research Design; Researchers; Sample size; Second Language Learning; Second language vocabulary learning; Second Languages; Statistical Analysis; Summative Evaluation; Systematic review; Task Analysis; Teaching Methods; Vocabulary; Vocabulary Development
• ISSN: 0272-2631; 1470-1545
• DOI: 10.1017/S0272263121000541

In this focused methodological synthesis, the sample construction procedures of 110 second language (L2) instructed vocabulary interventions were assessed in relation to effect size–driven sample-size planning, randomization, and multisite usage. These three areas were investigated because inferential testing makes better generalizations when researchers consider them during the sample construction process. Only nine reports used effect sizes to plan or justify sample sizes in any fashion, with only one engaging in an a priori power procedure referencing vocabulary-centric effect sizes from previous research. Randomized assignment was observed in 56% of the reports while no report involved randomized sampling. Approximately 15% of the samples observed were constructed from multiple sites and none of these empirically investigated the effect of site clustering. Leveraging the synthesized findings, we conclude by offering suggestions for future L2 instructed vocabulary researchers to consider a priori effect size–driven sample planning processes, randomization, and multisite usage when constructing samples.