Vocabulary size and comprehension of academic texts by Tanzanian university students: An exploratory study

Abstract This study aimed at determining the influence of vocabulary size on comprehension of academic texts among 256 university entrants to whom English was a foreign language (EFL) and a medium of instruction. The study was carried out at the University of Dodoma (UDOM) involving first-year students who were taking English Vocabulary Building as one of the core courses. The study used the vocabulary size test (VST) and a reading comprehension achievement test (RCAT). The results show that, on average, participants had a vocabulary size of 4 300 word families and the mean score of 39.83 in RCAT. With regard to relationship between scores of VST and RCAT, the results show that the two variables had positive correlation, r = 0.75, p < 0.001, and R2 = 0.565, indicating that about 56.5% of the variability in reading comprehension was explained by vocabulary size. Further, the linear regression analysis showed that B = 1.13, p < 0.0001, meaning that an increase of one score in VST (100 word families) influenced an increase of 1.131 in the text comprehension score.