Abstract
This paper is designed to address three research questions underlying the relationship between learners' vocabulary size and their reading comprehension. The first question investigated whether prospective test writers can agree on which reading skill was being tested by each question item. The second question explored which particular reading skill was difficult or easy for learners. The final question estimated the minimum vocabulary size needed to answer the reading questions on the National Center Test. The results of the first question showed that the judges had difficulty in reaching agreement on the skills purportedly being tested by particular items. For the second question item analyses were conducted on those test items with which judges had agreed on in the previous survey. The results revealed that a close relationship was not found between item difficulty and the type of reading skills tested by the question item. The results of the third question found that there was no clear-cut boundary for the threshold vocabulary knowledge to read the text reasonably well. However, the probable minimum vocabulary size was estimated at around 5000 words from the JACET 8000 word list.
