Decision Making
Time Trade-Off Task
Also called: composite time trade-off, health-state valuation
Measure values for imaginary health states through choices between ten years in a described state and fewer years in full health.
8-12 minUntimed
Free to start: 10 free participants per account, then $0.99 per participant for academic research, or any yearly plan. Try it here first, with no account.
- Papers, 2021 to 2025
- 566
- Evidence grade
- A
- Registered clinical studies
- 77
then death
What it measures
Values ten imaginary health states through choices between years in a described state and fewer years in full health. A lead-time follow-up measures values below zero. Reports values for each state and the mean across the fixed set.
Constructs
- Health-state valuation
- Preferences over health outcomes
Research uses
- Health economics research
- Health-state preference studies
- Within-study comparison of valuation methods
How the paradigm works
Ten original imaginary health states cover moving about, self-care, daily activities, pain and mood. They appear in a seeded order in all eight languages. These descriptions are not a licensed health questionnaire. Participants may stop at any time. No picture is shown and no points are paid.
More about the paradigm
Participants choose between ten years in the described state and an adjusting number of years in full health, with death after either life. The balance point divided by ten gives the state value. If immediate death is preferred to the state, ten years in full health are added before ten years in the state; the value then equals the full-health balance point minus ten, divided by ten.
Scores
- Mean Health-State Valuescore
- Mean of all ten state values. Null if any state is incomplete or beyond the measured range. Full health is 1; death is 0. Negative values come from the lead-time follow-up.
- Higher means the fixed set of imaginary states was valued more highly
- State 1 Valuescore
- Value of imaginary state 1. Null if incomplete or outside the measured range. The lower and upper limits locate the value.
- Describes choices about imaginary health states
- State 1 Lower Limitscore
- Lower endpoint of the search interval, or the one-sided bound. Null when there is no measured lower limit.
- Describes choices about imaginary health states
- State 1 Upper Limitscore
- Upper endpoint of the search interval, or the one-sided bound. Null when there is no measured upper limit.
- Describes choices about imaginary health states
- State 1 Lead-Time Follow-Upflag
- 1 if the value uses the lead-time time trade-off follow-up, 0 otherwise. Null if the state is incomplete.
- Identifies the elicitation method
- State 2 Valuescore
- Value of imaginary state 2. Null if incomplete or outside the measured range. The lower and upper limits locate the value.
- Describes choices about imaginary health states
- State 2 Lower Limitscore
- Lower endpoint of the search interval, or the one-sided bound. Null when there is no measured lower limit.
- Describes choices about imaginary health states
- State 2 Upper Limitscore
- Upper endpoint of the search interval, or the one-sided bound. Null when there is no measured upper limit.
- Describes choices about imaginary health states
- State 2 Lead-Time Follow-Upflag
- 1 if the value uses the lead-time time trade-off follow-up, 0 otherwise. Null if the state is incomplete.
- Identifies the elicitation method
- State 3 Valuescore
- Value of imaginary state 3. Null if incomplete or outside the measured range. The lower and upper limits locate the value.
- Describes choices about imaginary health states
- State 3 Lower Limitscore
- Lower endpoint of the search interval, or the one-sided bound. Null when there is no measured lower limit.
- Describes choices about imaginary health states
- State 3 Upper Limitscore
- Upper endpoint of the search interval, or the one-sided bound. Null when there is no measured upper limit.
- Describes choices about imaginary health states
- State 3 Lead-Time Follow-Upflag
- 1 if the value uses the lead-time time trade-off follow-up, 0 otherwise. Null if the state is incomplete.
- Identifies the elicitation method
- State 4 Valuescore
- Value of imaginary state 4. Null if incomplete or outside the measured range. The lower and upper limits locate the value.
- Describes choices about imaginary health states
- State 4 Lower Limitscore
- Lower endpoint of the search interval, or the one-sided bound. Null when there is no measured lower limit.
- Describes choices about imaginary health states
- State 4 Upper Limitscore
- Upper endpoint of the search interval, or the one-sided bound. Null when there is no measured upper limit.
- Describes choices about imaginary health states
- State 4 Lead-Time Follow-Upflag
- 1 if the value uses the lead-time time trade-off follow-up, 0 otherwise. Null if the state is incomplete.
- Identifies the elicitation method
- State 5 Valuescore
- Value of imaginary state 5. Null if incomplete or outside the measured range. The lower and upper limits locate the value.
- Describes choices about imaginary health states
- State 5 Lower Limitscore
- Lower endpoint of the search interval, or the one-sided bound. Null when there is no measured lower limit.
- Describes choices about imaginary health states
- State 5 Upper Limitscore
- Upper endpoint of the search interval, or the one-sided bound. Null when there is no measured upper limit.
- Describes choices about imaginary health states
- State 5 Lead-Time Follow-Upflag
- 1 if the value uses the lead-time time trade-off follow-up, 0 otherwise. Null if the state is incomplete.
- Identifies the elicitation method
- State 6 Valuescore
- Value of imaginary state 6. Null if incomplete or outside the measured range. The lower and upper limits locate the value.
- Describes choices about imaginary health states
- State 6 Lower Limitscore
- Lower endpoint of the search interval, or the one-sided bound. Null when there is no measured lower limit.
- Describes choices about imaginary health states
- State 6 Upper Limitscore
- Upper endpoint of the search interval, or the one-sided bound. Null when there is no measured upper limit.
- Describes choices about imaginary health states
- State 6 Lead-Time Follow-Upflag
- 1 if the value uses the lead-time time trade-off follow-up, 0 otherwise. Null if the state is incomplete.
- Identifies the elicitation method
- State 7 Valuescore
- Value of imaginary state 7. Null if incomplete or outside the measured range. The lower and upper limits locate the value.
- Describes choices about imaginary health states
- State 7 Lower Limitscore
- Lower endpoint of the search interval, or the one-sided bound. Null when there is no measured lower limit.
- Describes choices about imaginary health states
- State 7 Upper Limitscore
- Upper endpoint of the search interval, or the one-sided bound. Null when there is no measured upper limit.
- Describes choices about imaginary health states
- State 7 Lead-Time Follow-Upflag
- 1 if the value uses the lead-time time trade-off follow-up, 0 otherwise. Null if the state is incomplete.
- Identifies the elicitation method
- State 8 Valuescore
- Value of imaginary state 8. Null if incomplete or outside the measured range. The lower and upper limits locate the value.
- Describes choices about imaginary health states
- State 8 Lower Limitscore
- Lower endpoint of the search interval, or the one-sided bound. Null when there is no measured lower limit.
- Describes choices about imaginary health states
- State 8 Upper Limitscore
- Upper endpoint of the search interval, or the one-sided bound. Null when there is no measured upper limit.
- Describes choices about imaginary health states
- State 8 Lead-Time Follow-Upflag
- 1 if the value uses the lead-time time trade-off follow-up, 0 otherwise. Null if the state is incomplete.
- Identifies the elicitation method
- State 9 Valuescore
- Value of imaginary state 9. Null if incomplete or outside the measured range. The lower and upper limits locate the value.
- Describes choices about imaginary health states
- State 9 Lower Limitscore
- Lower endpoint of the search interval, or the one-sided bound. Null when there is no measured lower limit.
- Describes choices about imaginary health states
- State 9 Upper Limitscore
- Upper endpoint of the search interval, or the one-sided bound. Null when there is no measured upper limit.
- Describes choices about imaginary health states
- State 9 Lead-Time Follow-Upflag
- 1 if the value uses the lead-time time trade-off follow-up, 0 otherwise. Null if the state is incomplete.
- Identifies the elicitation method
- State 10 Valuescore
- Value of imaginary state 10. Null if incomplete or outside the measured range. The lower and upper limits locate the value.
- Describes choices about imaginary health states
- State 10 Lower Limitscore
- Lower endpoint of the search interval, or the one-sided bound. Null when there is no measured lower limit.
- Describes choices about imaginary health states
- State 10 Upper Limitscore
- Upper endpoint of the search interval, or the one-sided bound. Null when there is no measured upper limit.
- Describes choices about imaginary health states
- State 10 Lead-Time Follow-Upflag
- 1 if the value uses the lead-time time trade-off follow-up, 0 otherwise. Null if the state is incomplete.
- Identifies the elicitation method
- Completed Statescount
- States with a complete search and repeat check.
- Describes choices about imaginary health states
- Values Beyond the Rangecount
- States with a one-sided bound instead of a point value.
- Describes choices about imaginary health states
- Lead-Time Follow-Upscount
- Completed states valued using ten healthy years before ten years in the state.
- Describes choices about imaginary health states
- Repeat Agreement%
- Share of completed states with the same answer on the repeated comparison.
- Describes choices about imaginary health states
- Practice Answerflag
- 1 for a correct first practice answer, 0 for an incorrect answer.
- Describes choices about imaginary health states
- Median Choice Timems
- Median time to choose, excluding responses under 100 ms.
- Describes choices about imaginary health states
- Anticipationscount
- Choices made in under 100 ms; retained because choices determine later offers.
- Describes choices about imaginary health states
- Choices Recordedcount
- Choice responses, including anchors and repeats, excluding Stop.
- Describes choices about imaginary health states
Use and evidence
566 papers from 2021 to 2025 name this task in their title or abstract, down 11% compared with 2016 to 2020. That ranks it 46 of 582 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 131 |
| 2024 | 91 |
| 2023 | 98 |
| 2022 | 144 |
| 2021 | 102 |
| 2020 | 102 |
| 2019 | 123 |
| 2018 | 135 |
| 2017 | 134 |
| 2016 | 140 |
| 2015 | 131 |
| 2014 | 146 |
| 2013 | 127 |
| 2012 | 139 |
| 2011 | 117 |
| 2010 | 96 |
| 2009 | 124 |
| 2008 | 111 |
| 2007 | 84 |
| 2006 | 70 |
| 2005 | 79 |
| 2004 | 79 |
| 2003 | 56 |
| 2002 | 78 |
| 2001 | 61 |
| 2000 | 57 |
Use grade B
300 to 999 papers from 2021 to 2025.
Evidence grade A
At least 25 papers report its test-retest reliability and at least 25 registered clinical studies use it as an outcome.
- Papers on test-retest reliability
- 52
- Papers on reliability or validity
- 410
- Registered clinical studies using it as an outcome
- 77
Measured on ConductCognition
Pooled across the studies that feed our platform norms, by device group. A figure needs 50 or more people.
No pooled figure yet.
Note on the counts: Original imaginary health states; values describe the states, not a participant’s own health..
How the grades work
Use: A is 1,000 or more papers from 2021 to 2025, B 300 to 999, C 100 to 299, D 30 to 99 and E fewer than 30. Evidence: A means at least 25 papers report its test-retest reliability and at least 25 registered clinical studies use it as an outcome; B, at least 8 test-retest papers, and either 5 registered clinical studies or 150 reliability or validity papers; C, at least 2 test-retest papers, 30 reliability or validity papers or 3 registered clinical studies; D, little published measurement evidence found. The counts measure use. They include every paper that names the task in its title or abstract. Grades describe the published research on this task, not ConductCognition's version of it.
Source: ConductCognition test census 0.39.0, counted 10 November 2026 from OpenAlex and ClinicalTrials.gov.
Task design
The trial sequence as the test runs in ConductCognition.
- Health states
- 10 original states in all eight languages, in seeded order. Each has five descriptions: moving about, self-care, daily activities, pain and mood.
- Choices
- Participants choose between ten years in the described state and an adjusting number of years in full health, with death after either life. The balance point divided by ten gives the state value. If immediate death is preferred to the state, ten years in full health are added before ten years in the state; the value then equals the full-health balance point minus ten, divided by ten.
- Search
- 6 adjusting choices per state at standard settings, from 4 to 8. Each choice halves the remaining interval; the standard interval is 0.015625 wide. Equality ends the search early. Explicit anchors come first; one repeated comparison follows each state.
- Practice
- One question with feedback before the first state. Extra instructions introduce the lead-time follow-up when needed.
- Results
- Health-state values: 1 is full health, 0 is death. Reports each state’s value and interval limits, lead-time flags, the fixed panel mean, repeat agreement and completion. A bound is reported when the value is outside the measured range.
- Responses
- Untimed buttons on desktop, tablet and phone. Participants can stop at any time. Choices under 100 ms count as anticipations.
These original descriptions and unsupervised choices do not reproduce a licensed questionnaire or its population value set. Results value imaginary health states and do not assess the participant’s own health.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Choices have no correct answer. Answers under 200 ms on at least half the choices invalidate. Missing state values, values beyond the measured range, a changed answer on a repeated comparison and a wrong practice answer are flagged.
Why these rules
There is no correct option to compare with chance, so accuracy is not judged against chance. Equality or the same preference throughout can be meaningful. A repeated comparison checks response consistency without changing the value. An answer under 200 ms is faster than a simple visual reaction, so it cannot reflect the item. Following response-time effort screening for untimed tests (Wise and Kong 2005), the session is invalid only when at least half the answers are that fast.
No percentile. Scores and quality flags only.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Adjusting choices per state | 6 | 4 to 8 |
Yearly plans can change settings within these limits. Free and pay-as-you-go studies use the standard settings.
Need a setting this test does not have?
Devices and languages
- Untimed test: runs on desktops, laptops, tablets and phones. Participant devices
- Languages: English, Spanish, French, German, Italian, Portuguese (Brazil), Chinese (Simplified) and Japanese.
- Available on: Every plan, including the free plan.
- No percentile. Scores and quality flags only. How norms work
- Recruiting online? See the setup guides for Prolific, Sona Systems, CloudResearch Connect and Qualtrics.
Cite and describe
Participants completed the Time Trade-Off Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Janssen BMF, Oppe M, Versteegh MM, Stolk EA, 2013), with the standard settings (adjusting choices per state: 6). The main score was mean health-state value (mean of all ten state values).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Janssen, B. M. F., Oppe, M., Versteegh, M. M., & Stolk, E. A. (2013). Introducing the composite time trade-off: a test of feasibility and face validity. The European Journal of Health Economics, 14(Suppl 1), S5–S13. https://doi.org/10.1007/s10198-013-0503-2Conventional and lead-time choices and their value formulas; original descriptions and bisection in this implementation.
Source papers
- Janssen, B. M. F., Oppe, M., Versteegh, M. M., & Stolk, E. A. (2013). Introducing the composite time trade-off: a test of feasibility and face validity. The European Journal of Health Economics, 14(Suppl 1), S5–S13.Paradigm source, Adults
Questions
How long does the Time Trade-Off Task take?
About 8 to 12 minutes, as listed in the test library.
What device does a participant need?
Untimed test: runs on desktops, laptops, tablets and phones. The browser must be Chrome, Edge, Firefox or Safari.
What scores does it produce?
Mean Health-State Value, State 1 Value, State 1 Lower Limit, State 1 Upper Limit, State 1 Lead-Time Follow-Up, State 2 Value, State 2 Lower Limit, State 2 Upper Limit, State 2 Lead-Time Follow-Up, State 3 Value, State 3 Lower Limit, State 3 Upper Limit, State 3 Lead-Time Follow-Up, State 4 Value, State 4 Lower Limit, State 4 Upper Limit, State 4 Lead-Time Follow-Up, State 5 Value, State 5 Lower Limit, State 5 Upper Limit, State 5 Lead-Time Follow-Up, State 6 Value, State 6 Lower Limit, State 6 Upper Limit, State 6 Lead-Time Follow-Up, State 7 Value, State 7 Lower Limit, State 7 Upper Limit, State 7 Lead-Time Follow-Up, State 8 Value, State 8 Lower Limit, State 8 Upper Limit, State 8 Lead-Time Follow-Up, State 9 Value, State 9 Lower Limit, State 9 Upper Limit, State 9 Lead-Time Follow-Up, State 10 Value, State 10 Lower Limit, State 10 Upper Limit, State 10 Lead-Time Follow-Up, Completed States, Values Beyond the Range, Lead-Time Follow-Ups, Repeat Agreement, Practice Answer, Median Choice Time, Anticipations and Choices Recorded. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Time Trade-Off Task used in research?
566 papers from 2021 to 2025 name it in their title or abstract, down 11% compared with 2016 to 2020. That ranks it 46 of 582 test families in the ConductCognition test census (use grade B). Source: ConductCognition test census 0.39.0, counted 10 November 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Time Trade-Off Task have?
In the published research, 52 papers report its test-retest reliability and 77 registered clinical studies use it as an outcome (evidence grade A in the ConductCognition test census).
Does it report a percentile?
No. Scores and quality flags only.
Which settings can a researcher change?
Adjusting choices per state (4 to 8). Settings can be changed on yearly plans; free and pay-as-you-go studies use the standard settings.
Which languages can participants use?
Participants can take this test in English, Spanish, French, German, Italian, Portuguese (Brazil), Chinese (Simplified) and Japanese, with its words in the same language. English is on every plan, and the other languages come with yearly plans. Have a native speaker read the machine-translated text before launch.
Is this a clinical test?
No. ConductCognition is for research use only. It runs, scores and exports the test; clinical interpretation is outside the platform.
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