Readability Indices for Automatic Evaluation of Text Simplification Systems: A Feasibility Study for Spanish

This paper addresses the problem of automatic evaluation of text simplification systems for Spanish. We test whether already-existing readability formulae would be suitable for this task. We adapt three existing readability indices (two measuring lexical complexity and one measuring syntactic complexity) to be computed automatically, which are then applied to a corpus of original news texts and their manual simplifications aimed at people with cognitive disabilities. We show that there is a significant correlation between each of the three readability indices and several linguistically motivated features which might be seen as reading obstacles for various target populations. Furthermore, we show that there is a significant correlation between the two readability indices which measure lexical com-