6.44 The z distribution and comparing scores on two tests of English language learning: The Test of English as a Foreign Language (TOEFL), with scores ranging from 0 to 120, has traditionally been the most commonly used exam of reading comprehension, vocabulary, writing, and grammar for English-language learners in the United States. The International English Language Testing System (IELTS), with scores ranging from 0 to 9, has traditionally been the most commonly used exam in most other English-speaking countries (Ben, 2018). Does it matter which one is used? If a researcher wanted to compare English-language learners’ TOEFL and IELTS scores to see if they were equivalent, how could the researcher use z scores to test this?