The Tool for Automatic Measurement of Morphological Information (TAMMI).

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.