Spontane Taaldata En Het Meten Van Lexicale Rijkdom In Tweedetaalverwerving

Increasing use of spontaneous speech data in second language research made it necessary to use other measures than tests for getting insight into the lexical richness of (spoken) text corpora of second language learners. In this article several lexical measures (types, TTR, TTR(c), Guiraud, logTTR, Uber, theoretical vocabulary) are examined and discussed. On the basis of several studies that the TTR is the worst measure possible, but the better measures (types, Guiraud, theoretical vocabulary) are problematic too. Next, the characteristics of the lexical measures are examined by means of a few simple computer simulations with hypothetical lexica. The outcome is that neither the reliability, nor the validity of the different measures are satisfactory, especially with respect to the TTR.