ABSTRACT
This study documents and assesses the Tool for Automatic Measurement of Morphological Information (TAMMI), which calculates measures related to basic morpheme counts, morphological variety, morphological complexity, morpheme type-token counts, and variables found in the MorphoLex database (Sánchez-Gutiérrez et al., 2018) including morpheme frequency/length, morpheme family size counts and frequency, and morpheme hapax counts. These measures are assessed in two studies that include a word frequency measure as a control variable. The first study examined links between morphological variables and judgements of reading ease in a corpus of ~ 5000 reading excerpts, finding that variables related to derivational variety, word frequency, affix frequency, and morpheme counts explained 40% of the variance in the reading scores. The second examined links between morphological variables and human assessments of vocabulary proficiency in a corpus of ~ 7000 essays written by English-language learners (ELLs), finding that the number of morphemes, morpheme variety, and the number of roots explained 21% of the variance in the human assessments.
