Module 11 · Part 3 · Data Collection

Designing Questionnaires

Design questionnaires that produce high-quality, analyzable data, and that participants actually complete.

Patient Registries 101 · Dr. Danielle Boyce · EpilepsyLive

The questionnaire design imperative

A poorly designed questionnaire produces poor data.
Too long , Completion rates drop dramatically beyond 15 to 20 minutes
Ambiguous questions , "How severe are your symptoms?" means different things to different people
Double-barreled questions , "Do you have pain and fatigue?" cannot be answered with a single yes/no
Custom scales instead of validated instruments , Produces uninterpretable data
No skip logic , Showing irrelevant questions wastes participant time and increases abandonment

PROMIS (NIH): Physical function, fatigue, pain, sleep, anxiety, depression, social participation → healthmeasures.net
EQ-5D: Generic health related quality of life; widely used in health economics → euroqol.org
SF-36 / RAND-36: General health status → rand.org/health-care/surveys_tools/mos/36-item-short-form.html
NIH Toolbox: Cognitive, emotional, motor, and sensory function → nihtoolbox.org
Participant-specific instruments: Many diseases have gold-standard disease specific instruments.

For symptom severity, use numeric rating scales (NRS) or Likert scales, not free text.
NRS 0 to 10: "On a scale of 0 to 10, how severe is your pain today?", Simple, widely understood
Likert (5-point): Never / Rarely / Sometimes / Often / Always, Good for frequency
Visual analog scale (VAS): Continuous line from "None" to "Worst imaginable", More sensitive but harder to implement on paper

For onset dates, provide a structured date picker with a "year only" or "approximate" option, many participants know the year of symptom onset but not the exact date.

Use skip logic so participants only see relevant questions
"Have you ever had seizures?" → If NO, skip to next section
"What medications are you currently taking?" → If NONE, skip medication detail section

Draft based on scientific questions and SAB input
Participant review , share draft with 3 to 5 participants for comprehension testing
Cognitive interviewing , ask participants to "think aloud" as they answer questions
Pilot test with 20 to 50 participants; measure completion rate and time
Analyze pilot data , Are there items with very high "don't know" or skip rates? Do items perform as expected statistically?
Revise based on pilot findings

Enrollment questionnaire: Budget 20 to 30 minutes maximum for core elements
Annual/biannual follow up: 10 to 15 minutes
Brief check-ins: 5 minutes or less for high-frequency (quarterly or monthly) touchpoints
Shorter and more frequent is often better than long and infrequent, and yields better longitudinal data.