MODELING LEMMA FREQUENCY BANDS FOR LEXICAL COMPLEXITY ASSESSMENT OF RUSSIAN TEXTS

Abstract

The paper is devoted to the problem of modeling general-language frequency using data of large Russian corpora. Our goal is to develop a methodology for forming a consolidated frequency list which in the future can be used for assessing lexical complexity of Russian texts. We compared 4 frequency lists developed from 4 corpora (Russian National Corpus, ruTenTen11, Araneum Russicum III Maximum, Taiga). Firstly, we applied rank correlation analysis. Secondly, we used the measures “coverage” and “enrichment”. Thirdly, we applied the measure “sum of minimal frequencies”. We found that there are significant differences between the compared frequency lists both in ranking and in relative frequencies. The application of the “coverage” measure showed that frequency lists are by no means substitutable. Therefore, none of the corpora in question can be excluded when compiling a consolidated frequency list. For a more detailed comparison of frequency lists for different frequency bands, the ranked frequency list, based on RNC data, was divided into 4 equal parts. Then 4 random samples (containing 20 lemmas from each quartile) were formed. Due to the wide range of values, accepted by ipm measure, relative frequency values are difficult to interpret. In addition, there are no reliable thresholds separating high-frequency, mid-frequency, and low-frequency lemmas. Meanwhile, to assess the lexical complexity of texts, it is useful to have a convenient way of distributing lemmas with certain frequencies over the bands of the frequency list. Therefore, we decided to assign lemmas “Zipf-values”, which made the frequency data interpretable because the range of measure values is small. The result of our work will be a publicly accessible reference resource called “Frequentator”, which will allow to obtain interpretable information about the frequency of Russian words.