Mobile display of choice tasks in patient surveys

More than half of patient preference study respondents complete surveys on mobile devices. Choice tasks designed for desktop display degrade severely on small screens.

How to design and test DCE choice tasks for mobile display in patient preference studies.

Ben White, 07.07.2026

The mobile display problem

A choice task designed for a 1920px desktop monitor may present 5 attributes across 3 alternatives in a readable table. On a 375px mobile screen, the same table either overflows horizontally (requiring horizontal scrolling to see all alternatives) or compresses to the point of illegibility.

Respondents who cannot read the choice task clearly cannot make valid choices. Mobile display problems are a source of systematic measurement error that is invisible in the data - incomprehensible choice tasks look identical in the data file to comprehensible ones.

Why mobile optimisation matters in health research

Patient populations have higher mobile completion rates than general population samples. Patients who are unwell, in hospital, or with limited mobility are more likely to complete surveys on phones than on desktops.

Mobile display testing is not an optional quality check. It is a necessary part of survey design for any study where mobile completion rates are expected to exceed 20%.

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Optimising choice task display in SurveyEngine

Step 1: Test on a physical mobile device, not just a browser developer tools simulation. Developer tools simulate screen size but not touch interactions, font rendering, or OS-specific behaviour.

Step 2: Test on both iOS and Android. The two platforms render HTML and CSS differently. A choice task that displays correctly on iOS may overflow or compress on Android.

Step 3: Limit the number of alternatives for mobile studies. 3-alternative choice tasks are readable on mobile; 4-alternative tasks typically require horizontal scrolling which reduces engagement.

Step 4: Use responsive CSS. Table-based choice tasks are difficult to make responsive. CSS grid or flexbox layouts adapt more reliably across screen sizes.

Step 5: Monitor mobile completion rates and task times separately. If mobile users have significantly different completion rates, dropout patterns, or WTP estimates, report this as a potential data quality issue.

Worked example - oncology patient survey mobile optimisation

A patient preference study in a chronic pain condition has 58% mobile completion rate from the soft launch data. Mobile task completion times average 34 seconds per task versus 22 seconds for desktop - indicating higher cognitive load on mobile.

The choice task layout is redesigned from a 3-column table to a 2-column stacked layout optimised for mobile. In the re-pilot, mobile task times fall to 26 seconds and mobile-desktop WTP differences become statistically insignificant.