a) Relevance & Research question: Although the use of progress bar seems to be standard in many online surveys, there is no consensus in the literature regarding its effect on survey drop-off rates. Researchers hope that using a progress bar helps reducing drop-off rates by providing respondents with a sense of survey length and allowing them to monitor their progress through it.
b) Methods & Data: In this meta-analysis we analyzed 27 randomized experiments that compared drop-off rates of an experimental group who completed an online survey where a progress bar was shown, to drop-off rates of a control group to whom the progress bar was not shown. In all the studies drop-offs were defined as any respondent who did not fully complete the survey. Three types of bars were analyzed: a) linear or constant, b) fast first then slow, and c) slow first then fast.
c) Results: Random effects analysis was used to compute odds ratios (OR) for each study. Because the dependent variable was drop-off rate, an OR greater than 1 indicates that the progress bar group had a higher drop-off rate while an OR lower than 1 indicates that the progress bar group had a lower drop-off rate. The OR for the 13 studies using a constant progress bar is 1.065 (p=0.304). The OR for the 7 studies using fast-to-slow progress bar is 0.835 (p=0.131), whereas the OR for the 7 studies presenting the slow-to-fast progress bar is 1.564 (p=0.002). These preliminary results suggest that, contrary to widespread expectations, the progress indicator does not help reduce drop-off rates for the constant progress indicator while there is some indication that the fast to slow does. Furthermore, the slow-to-fast bar increases drop-off rates as compared to not showing the progress bar. We do not suggest using the fast to slow progress indicator because ethically questionable and against AAPOR and ESOMAR codes.
d) Added value: To our knowledge this is the first meta-analysis study on the topic. Additional literature search will be performed and we are awaiting from some authors to send us data to add to the study.