> ## Documentation Index
> Fetch the complete documentation index at: https://docs.liveclin.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Ideal length
> How many questions a weekly follow-up questionnaire should have: what the evidence shows about drop-off, response fatigue, and the time budget.
A long questionnaire doesn't give you less data. It gives you **worse data** — the more dangerous of the two problems, because bad data looks like good data on a chart. Before people abandon a questionnaire, they start answering on autopilot.
This page summarizes what the evidence shows about questionnaire length and turns it into practical numbers for weekly follow-up.
## What the evidence shows
SurveyMonkey analyzed about 100,000 questionnaires from its own base and published two relevant findings:
* The sharpest increase in drop-off comes with each question added up to around the fifteenth; after that, each extra question costs less than the first ones did.
* Abandonment rises once completion takes more than seven to eight minutes, with the completion rate falling between 5% and 20%.
Kantar reached numbers pointing the same way: a questionnaire over 25 minutes loses more than three times as many respondents as one under five.
## Clinical practice is stricter than those numbers
The data above comes from respondents who fill something in **once**. You are going to send the same questionnaire to the same person 4, 12, 50 times.
The ecological momentary assessment (EMA) literature calls this **assessment fatigue**. The 4HAIE cohort study, published in 2026 in the International Journal of Behavioral Medicine, recorded a drop in participation across successive blocks even among highly engaged participants, and even with active reminders. A randomized trial published in JMIR in 2025 tested the other side: holding total load constant, half the questionnaires every two weeks preserved the response rate better than all the questionnaires every four weeks.
In short: a short questionnaire answered twelve weeks in a row is worth more than a complete questionnaire answered twice and then abandoned.
None of these studies were run with private-practice patients answering on WhatsApp, with an active therapeutic bond and paying for the follow-up. It's plausible that tolerance here is higher, because the person has a direct interest in the result. Treat the numbers below as a conservative starting point, not as a measurement of your own audience.
## The recommendation
| Parameter | Recommendation |
| ---------------------------- | ------------------------------------------------------- |
| Number of questions | 8 to 12 |
| Floor | 5 (below that the patient doesn't do enough reflecting) |
| Absolute ceiling | 15 |
| Target answering time | 90 to 180 seconds |
| Open questions | at most 1 required; a second one may exist, optional |
| Photo upload | biweekly at most, always optional |
| Fixed vs. rotating questions | about 70% fixed, 30% tied to the current cycle |
## Time budget by question type
Add up your questionnaire's time before you save. If it goes over 180 seconds, cut something.
| Response mode | Average time |
| ------------------------------------------ | ------------ |
| Linear scale | 5 s |
| Emoji scale | 5 s |
| Single choice (up to 5 options) | 8 s |
| Number | 8 s |
| Metric (requires measuring something) | 10 s |
| Single choice with a triggered explanation | 30 s |
| Open answer | 60 s |
| Photo upload | 90 s |
A 10-question questionnaire within budget: seven scales (35 s), one single choice with an explanation (30 s), one metric (10 s), and one open answer (60 s) add up to 135 seconds.
## Next steps
Spread the 8 to 12 questions across the five-block architecture.
Pick the right response mode for each question.
* SurveyMonkey, *Survey completion times* and *Does adding one more question impact survey completion rate?*, aggregate analysis of about 100,000 surveys.
* Kantar, benchmarks on abandonment above 7 to 8 minutes of completion time.
* 4HAIE cohort study on EMA adherence and wearable monitoring. *International Journal of Behavioral Medicine*, 2026.
* Randomized trial on app-based questionnaire delivery patterns and longitudinal response rate. *JMIR*, 2025.