Many students and institutions have questions about the differences between Duolingo English Test (DET) and IELTS Academic for academic study. Research carried out by experts at Georgia State University shows that there are big differences between the two tests in terms of their suitability for recruiting students for higher education courses.
Here is a quick recap of the findings, which will help you discover how the two tests compare and what it means for you.
IELTS Academic is a more complete test of the skills students need in higher education
DET does not cover all of the key language skills needed for academic success because it concentrates on vocabulary and grammar, while IELTS Academic covers a much wider range of communicative skills across all four language skills – listening, reading, writing and speaking.
Skills covered by the two tests
Listening
IELTS
Test items elicit the following skills:
- Understand main ideas and detailed factual information
- Understand the opinions and attitudes of speakers
- Understand the purpose of an utterance
- Follow the development of ideas
DET
Test items elicit the following skills:
- Distinguish words from non-words presented aurally
- Transcribe sentences presented aurally; hold input in short-term memory long enough to transcribe sentences
Summary: Listening appears to be the most under-represented of all the skills in DET, compared with IELTS. DET appears to be based solely on intensive listening for vocabulary and grammatical structures, rather than listening for meaning or to understand the gist of extended discourse, which are essential skills for academic success.
Reading
IELTS
Test items elicit the following skills:
- Read for the general sense of a passage
- Read for main ideas and details
- Understand inferences and implied meanings
- Recognize writer’s opinions, attitudes, and purposes
- Follow the development of an argument
DET
Test items elicit the following skills:
- Distinguish English words from non-words
- Read and complete: Use lexical and syntactic knowledge to complete gapped words in a short passage
- Interactive Reading: five item types as follows:
- Complete sentences with gapped words
- Complete paragraphs with gapped sentence
- Locate the answer to a comprehension question
- Choose the idea that is present in the text
- Choose the best title for the text
Summary: A detailed comparison between the IELTS Academic Reading and the DET Reading section reveals that DET assesses a much narrower range of reading purposes and cognitive processes.
Writing
IELTS
Task description:
- Describe or explain information presented in a chart, graph or table
- Write an essay in response to a point of view, argument or problem
DET
Task description:
- Write at least one sentence describing a photo
- Write a short response to a question prompt
Summary: To our knowledge, Duolingo does not provide examples of scripts from any of the Writing tasks, so it is impossible to provide comparative data. However, given the general nature of the prompts and the brevity of expected responses (at least 50 words, maximum of five minutes) it would be surprising to find similar levels of lexical and syntactic complexity, or a variety of cohesive devices, in DET written responses.
Speaking
IELTS
Test items elicit the following skills:
- Providing personal information
- Expressing and justifying opinions
- Expressing preferences
- Explaining, suggesting, speculating, comparing, summarizing, narrating1
DET
Test items elicit the following skills:
- Providing personal information
- Expressing and justifying opinions
- Explaining, describing, narrating
Summary: while both tests require spoken production and invoke at some level the skills involved in monologue speaking, they are not at all equivalent in terms of spoken interaction. In DET, there is no opportunity to demonstrate the ability to interact with another speaker in real time.
1 This list comes from Taylor and Chan’s (2015) analysis; other discourse management functions may be possible.
Comparison of the skills elicited by IELTS Academic and Duolingo English Test
Listening skills invoked in responding to test items
IELTS
- Input decoding
- Lexical search
- Parsing
- Meaning construction
DET
- Input decoding
- Lexical search
- Parsing
- Meaning construction
Reading skills invoked in responding to test items
IELTS
- Word recognition2
- Lexical access3
- Syntactic parsing4
- Establishing propositional meaning
- Inferencing
- Building a mental model
- Creating a text-level representation
DET
- Word recognition
- Lexical access
- Syntactic parsing
- Establishing propositional meaning
- Inferencing
- Building a mental model
- Creating a text-level representation
2 Skills in parenthesis are not directly tested, but are enabling skills to complete other reading tasks.
3 Skills in parenthesis are not directly tested, but are enabling skills to complete other reading tasks.
4 Skills in parenthesis are not directly tested, but are enabling skills to complete other reading tasks.
Reading goals
IELTS
- Careful reading: Local
- Careful reading: Global
- Expeditious reading: Local
- Expeditious reading: Global
DET
- Careful reading: Local
- Careful reading: Global
- Expeditious reading: Local
- Expeditious reading: Global
Writing skills invoked in responding to test items
IELTS
- Microplanning
- Translation
- Monitoring
- Macroplanning
- Organization
- Revising
DET
- Microplanning
- Translation
- Monitoring
- Macroplanning
- Organization
- Revising
Speaking skills invoked in responding to test items
IELTS
- Grammatical encoding
- Morpho-phonological encoding
- Phonetic encoding
- Articulation5
- Conceptualization
- Self-monitoring
DET
- Grammatical encoding
- Morpho-phonological encoding
- Phonetic encoding
- Articulation
- Conceptualization
- Self-monitoring
5 Conceptualization: may be invoked only minimally, given the brevity of the task
Speaking interaction pattern
IELTS
- Planning time allowed
- Reciprocal interaction (face-to-face)
- Sustained speaking on a topic for more than 30 seconds
DET
- Planning time allowed
- Reciprocal interaction (face-to-face)
- Sustained speaking on a topic for more than 30 seconds
The materials and topics in IELTS are more academically oriented
IELTS Academic focuses on authentic academic content and interactions, ensuring every test is fit for purpose and relevant for what a test taker needs once they get to university.
The test materials in DET are written in a more familiar way and do not focus on academic language, which means DET may have limitations for higher education institutions in terms of predicting academic success.
Comparison of the contextual features in IELTS Academic and Duolingo English Test
Contextual differences for Listening
Nature of the information
IELTS
- Only concrete
- Mostly concrete
- Fairly abstract
- Mainly abstract
DET
- Only concrete
- Mostly concrete
- Fairly abstract
- Mainly abstract
Discourse mode
IELTS
- Descriptive
- Historical/biographical
- Expository
- Argumentative
- Instructive
DET
- Descriptive
- Historical/biographical
- Expository
- Argumentative
- Instructive
- Even though both tests cover social and academic domains, IELTS Listening input is significantly longer and is presented in much more varied discourse modes.
- IELTS test passages include a variety of speaker accents, while DET appears to include standard American accents only.
- IELTS Listening tasks require a higher level of retention of information. IELTS Listening has more extended listening input for test takers to process from listening to each passage only once. DET Listening tasks are typically shorter and allow listeners to listen to the materials more than once.
Contextual differences for Reading
Nature of the information
IELTS
- Only concrete
- Mostly concrete
- Fairly abstract
- Mainly abstract
DET
- Only concrete
- Mostly concrete
- Fairly abstract
- Mainly abstract
Discourse mode
IELTS
- Descriptive
- Historical/biographical
- Expository
- Argumentative
- Instructive
DET
- Descriptive
- Historical/biographical
- Expository
- Argumentative
- Instructive
- The texts presented by IELTS reflect academic texts more closely. They are more abstract and include argumentation, a very common rhetorical mode in academic writing.
- IELTS uses non-verbal information and requires test takers to combine verbal and visual information, while DET does not.
- DET tasks at the highest level tend to be much shorter and syntactically less complex than IELTS Reading passages.
- IELTS passages are overall more complex, with longer sentences and clauses, and more coordinated phrase and complex nominals.
Contextual differences for Writing
Nature of the information
IELTS
- Only concrete
- Mostly concrete
- Fairly abstract
- Mainly abstract
DET
- Only concrete
- Mostly concrete
- Fairly abstract
- Mainly abstract
Discourse mode
IELTS
- Descriptive
- Historical/biographical
- Expository
- Argumentative
- Instructive
DET
- Descriptive
- Historical/biographical
- Expository
- Argumentative
- Instructive
- Given the general nature of the test prompts in DET and the brevity of the expected response (at least 50 words, maximum of 5 minutes), it would be surprising to find similar levels of lexical and syntactic complexity and cohesive devices in DET written responses compared to those in IELTS Academic.
Contextual differences for Speaking
Nature of the information
IELTS
- Only concrete
- Mostly concrete
- Fairly abstract
- Mainly abstract
DET
- Only concrete
- Mostly concrete
- Fairly abstract
- Mainly abstract
Discourse mode
IELTS
- Descriptive
- Historical/biographical
- Expository
- Argumentative
- Instructive
DET
- Descriptive
- Historical/biographical
- Expository
- Argumentative
- Instructive
- IELTS Speaking tasks appear to be more abstract and academically oriented, whereas DET speaking topics appears to be more familiar.
- IELTS Speaking has much greater construct (skills) coverage than DET. Particularly at the lower levels, DET prompts tend to be descriptive in nature (e.g. talk about a hobby or activity you enjoy).
Test scores should be compared with caution
The research findings remind us that it is difficult to make score comparisons between two very different tests and institutions should not just rely on simple conversion tables to understand what scores mean. Looking closely at what is tested is more informative to ensure that test takers have the right language skills and confidence to follow an academic course successfully.
Why test scores should be compared with caution
Duolingo has produced a concordance table between IELTS and DET scores, however the researchers suggest that the relationship between the two tests is not straightforward and the relationship needs to be interpreted with caution.
Why do we need to be cautious?
Well firstly, the current concordance table is too simplistic a comparison that doesn’t tell us much from a research perspective, and no independent researcher has produced further research to the best of our knowledge.
Secondly, comparisons between scores on different tests is challenging because tests differ in their design, purpose and format (Taylor, 2004, Lim et al, 2013) and the greater the difference in design, the more problematic the comparison is.6
6 Taylor, L. (2004). Issues of test comparability, Research Notes 15, 2–5.
Lim, G. S., Geranpayeh, A., Khalifa, H., & Buckendahl, C. W. (2013). Standard setting to an international reference framework: Implications for theory and practice, International Journal of Testing.
What is important when comparing tests?
The Studies in Test Comparability Series encourages test score users to move beyond a basic comparison of overall scores to a more nuanced awareness of underlying similarities and differences.
“Institutions should consider a range of evidence when setting standards for their specific purposes, as the range of activities sampled by different tests (and the depth in which they do so) differs … the applicability of scores may vary, depending on the range of activities in which applicants will typically be engaged.”7
For test scores to be truly meaningful, we need to broaden our focus beyond simply the language, to focus also on the underlying cognitive demands of the test task. For example, do they reflect the demands of real world language use? We need to understand the social conditions of language use, particularly for speaking.
We also need to compare the scores achieved across the different sections of a test, to draw comparisons around the measurement relationship between the two and answer questions such as how well one test can predict performance on the other.
Further research will be needed in order to meaningfully compare the scores on IELTS Academic and DET.
7 Saville, N., O’Sullivan, B, & Clark. T. (Eds.) (2021). Investigating the relationship between IELTS and PTE-Academic. IELTS Partnership Research Papers: Studies in Test Comparability Series, No. 2. IELTS Partners: British Council, Cambridge Assessment English and IDP: IELTS Australia.
IELTS Academic is more transparently aligned to the CEFR
The Common European Framework of Reference for Languages (CEFR) is an international standard for describing language ability. Different exams report results in relation to the CEFR but there are big differences in the way they do this.
IELTS scores are linked to the levels of the CEFR by research and validation studies carried out over many years, and this information is available on the IELTS website and in academic publications.
The researchers were unable to find any publicly available information about how DET maps its scores onto the CEFR and recommend that the CEFR levels provided by Duolingo are interpreted with caution.
Find out more about IELTS Academic and the CEFR
What does this mean for universities?
The key conclusion for you to take away is that DET test tasks are less academically oriented and heavily weighted towards vocabulary and grammar. A test that focuses on these skills can be useful for making rough distinctions between learners, but universities are recommended to be aware of the limitations of DET in terms of predicting academic success and to compare DET test scores with caution.
IELTS Academic covers vocabulary and grammar, but it also includes in-depth assessment of communication skills and the ability to understand and use language in academic contexts. The face-to-face Speaking test and the extensive Writing paper mean that IELTS test scores reflect the ability to use the language required in the real world.