For the summer 2019 updates, Duolingo relied on feedback and research from the language testing community, admissions professionals, counselors, and test takers.
In the Duolingo English Test technical manual, see section 5.5 - 5.6 under “Item Description” for an explanation of these test items as well as the underlying research into their efficacy.
See section 6.4 in the “Development, Delivery, & Scoring” for more information about their scoring and reliability.
See section 7, “Statistical Characteristics” for an explanation of the test scale, score distribution, reliability measurements, and relationship to the TOEFL iBT® and IELTS® Academic. For specific concordances, visit our scores page.
Usage data and feedback from admissions offices revealed that, on average, institutions have less than 5 minutes to review the video interviews and writing samples of each candidate. In addition, they specifically sought out responses where the student had the most to say about the topic. The new format keeps the video interview and writing sample efficient while eliciting the most insightful responses.