[Measurement of the legibility of written texts. Correlation between the Flesch manual method and computer methods]

To compare, for the calculation of the Flesch legibility index, the original manual method and the computer programmes Word Perfect 7 and Microsoft Word 2000; and to correlate these with other computer measurements of legibility.

Descriptive, observation study.

A Madrid Health Centre, within a study of the legibility of health education (HE) leaflets.

A sample of text from 100 HE leaflets and 11 general control texts. Main measurements. The 11 texts were analysed through Flesch' s original manual method and the computer programmes mentioned, with which the number of words and sentences, the Flesch scores, the index of sentence complexity and the LEGIN index were calculated. Pearson's correlation coefficient was calculated for all the variables.

There was very good correlation between the manual measurement of the Flesch index, the number of words and sentences, and their determination by means of computers (r>0.75); and excellent correlation between the two programmes (r>0.9). The results support the cut-off scores in other studies for legibility measured by computer.

Measurement of legibility through the computer programmes used can reliably replace manual measurement of the Flesch index.