A Longitudinal Study Of Accuracy, Complexity and Variability

The purpose of the present study was to apply Dynamic Systems Theory (DST) methodology, comparing and evaluating the use of various measures of complexity and accuracy in light of DST, looking for different stages of stability or variability in the extended longitudinal development of advanced written English (L2) in a Dutch (L1) subject. Fortynine texts produced in two non-concurrent phases over a period of 13 years were analysed using 17 different measures of complexity and accuracy. Clear evidence was found for the existence of: stages of high variability followed by attractor states, changing relations between variables, and non-linear development, all in line with DST. Out of the different groups of measures, the ones outlining dynamic development most strongly in our advanced learner were: Customised Lexical Frequency Profile, Average Sentence Length and Average Noun Phase length, Sentence Complexity (counting compound and compound-complex sentences) and Lexical and Syntactic Errors. Lexical Density and Type-Token Ratio were deemed weak. Finally, a new measure, Lexico-Syntactic Finite Verb Ratio (LSFVR), showed moderate dynamic growth at advanced proficiency levels but correlated strongly and significantly with all other measures, implying potential usefulness for future studies.