Giddy up! Can We Reduce Dropouts in a Discrete-Choice Experiment by Including an Encouraging Message? A Randomised...

Discrete-choice experiments (DCEs) are valuable in establishing health preferences. However, their repetitive nature may cause dropouts.

Does an encouraging 'giddy-up' message improve completion rates, data quality and respondent experience?

Two online DCEs in Australia: 1) breast cancer screening (women aged 40-75 y) and 2) arm therapy (stroke survivors aged >18 y). We randomised participants to see 10 to 12 choice sets continuously or with a social exchange theory-based giddy-up message halfway. Conditional binomial statistics compared dropout rates as our primary outcome. Secondary outcomes included completion time, difficulty and preference consistency.

From 867 screening and 333 stroke respondents, the dropout rates were 7% and 28%, respectively. Among those who completed >50% of the choice sets, there was no significant difference in dropout rates between arms (screening: 1.5% control, 0.75% giddy-up, P = 0.35; stroke: 1.7% control, 4.1% giddy-up, P = 0.30). There were no significant differences in secondary outcomes, except in the screening survey, in which the giddy-up reduced difficulty (5% vs 2%, P = 0.03) and improved understanding (18% vs 12%, P = 0.01).

A DCE giddy-up message appears to have little impact on completion, although it may make the survey feel easier to complete.

A giddy-up message is unlikely to be useful in online, adult DCEs.