Variability as predictor in L2 writing proficiency

Lowie and Verspoor (2019) had an unexpected finding in their work Individual Differences and the Ergodicity Problem: The main predictor for proficiency gains in 22 beginning Dutch learners of English over one year was not traditional individual difference (ID) factors, but the degree of variability that occurred over time. We speculate that variability might stand for “investment” as students might strive for an excellent product at one time, but are not able to reach quite the same level the next time. The current paper sets out to see whether the findings can be replicated with a different population and finer-tuned measures. The English writing proficiency of 22 L1 Chinese adults at the university level was measured with 12 texts scored holistically over one academic year. The degree of variability in L2 writing was operationalized as the coefficient of variation (CoV), which was calculated as the standard deviation divided by the mean of the L2 writing holistic scores. ID factors measured were motivation, language aptitude, and working memory. The findings were as follows: None of the ID factors predicted the final L2 writing proficiency nor the L2 writing proficiency gains, but the CoV did. The implications of these findings are discussed.