Dropout rate

Of 500 people who started a survey, 180 closed the page before reaching the end. The dropout rate is the percentage of respondents who started a survey but did not submit their answers (they left before the final screen). It is the "inverse" metric of completion rate: dropout rate = 100% − completion rate. In the SurveyNinja glossary, the same idea is described by the term abandonment rate. A high dropout rate points to problems with the length, complexity, or usability of the survey.

It is useful to analyze the dropout rate together with the question or screen where respondents tend to leave. This helps you find the "bottlenecks" and reduce drop-off by shortening the survey, using logic jumps, or simplifying the wording.

The shorter and clearer the survey, the lower the dropout rate usually is. Long surveys with no branching and a large number of required fields tend to produce a high drop-off; a pilot helps you assess this before the main data collection.

What the dropout rate is in plain terms

Dropout rate is the percentage of respondents who started a survey (opened the first page or answered the first question) but did not complete it — they closed the page, stopped answering, or never reached the form submission. It is calculated as (number who started − number who completed) / number who started × 100%, or as 100% − completion rate. A high dropout rate indicates drop-off during the survey and is often linked to survey fatigue, survey length, or difficult questions.

Put simply: the dropout rate is "how many of those who started did not reach the end." If 30 out of 100 who started left along the way, the dropout rate is 30%.

Why measure the dropout rate

Assessing losses across the funnel. It shows what share of respondents is "lost" between the start and the finish of the survey. A high dropout rate is a signal to rethink the survey design.

Finding problem spots. If the platform stores data on which question a respondent left at, you can build a drop-off funnel by screen and find the questions after which drop-off is the highest.

Link to data quality. Those who stay and complete the survey when drop-off is high may differ systematically from those who left — in that case the sample is biased. Tracking the dropout rate reminds you of this limitation when interpreting the results.

How the dropout rate is calculated

Dropout rate = (number who started − number who completed) / number who started × 100%, or 100% − completion rate.

"Started" and "completed" are defined the same way as when calculating the completion rate. In SurveyNinja, this uses data on incomplete and completed responses; for more detail, see the help article on incomplete responses.

What affects the dropout rate

Length and volume. Long surveys and long series of similar questions increase fatigue and the dropout rate. Short surveys and logic jumps usually reduce drop-off.

Required and difficult questions. A large number of required fields or questions that people "get stuck" on raise the risk of leaving. Moderate use of required questions and clear wording reduce dropout.

Usability and loading. An inconvenient interface on mobile, slow page loading, or connection drops increase the dropout rate regardless of the content.

Relationship to other metrics

The dropout rate and the completion rate together add up to 100% for those who started the survey. What they share with the response rate is that all three describe the survey "funnel": invited → started → completed. In a report it is useful to state both the response rate (of those invited) and the completion rate or dropout rate (of those who started), so the picture is complete.

Common mistakes

Confusing it with the non-response rate. The dropout rate covers only those who started the survey. Those who did not open the link or did not click "start" are not included in the dropout rate (they are counted in the response rate).

Ignoring it when interpreting results. A high dropout rate means conclusions are drawn from a subset of those "who reached the end"; this should be stated explicitly in the methodology and limitations.

Mixing it up with declining the invitation. "Did not open the link" and "opened it but did not complete" are different stages of the funnel. The dropout rate refers only to the second; for the first, the response rate of those invited is used.

How this looks in SurveyNinja

SurveyNinja counts those who started and those who completed the survey; from this data it calculates the completion rate and the dropout rate. Incomplete responses are saved and available for analysis — you can see which question respondents most often stop at and adjust the survey. For more on working with incomplete responses, see the SurveyNinja help article.

In a report or methodology, state the dropout rate next to the completion rate: "Of N who started the survey, M completed it (completion rate X%); the dropout rate was Y%." This lets the reader see the full funnel and understand at which stage respondents are lost. If the dropout rate is high, the study's limitations should mention possible sample bias due to drop-off.

Example of use

Of 600 people who opened a 12-question NPS survey, 420 reached the end. Dropout rate = (600 − 420) / 600 × 100% = 30%. The data on incomplete responses shows that about half of those who left stopped at question 7 (an open-ended field, "Why did you give this score?"). The fix: make the question optional or move it to the end — after the change, the dropout rate fell to 22% and the completion rate rose.

It is important not to confuse the dropout rate with the non-response rate to the invitation: those who did not open the link are not included in the dropout rate. The full picture: invited → started (opened the survey) → completed. The response rate is measured against those invited, and the dropout rate against those who started.

Practical recommendations

State the dropout rate in the report. For example: "The dropout rate was N% (M out of K who started did not complete the survey)."

Analyze drop-off by screen. Use data on incomplete sessions to find the questions with the highest drop-off.

Reduce drop-off through content. Shorten the survey, add branching, reduce the number of required questions, and simplify the wording in the "bottleneck" spots.

Cross-check against the completion rate. The dropout rate and the completion rate add up to 100%; verifying this equality helps confirm that "started" and "completed" were counted correctly.

Interpreting it in a report

A high dropout rate (for example, above 40–50%) is not a verdict but a signal. State it in the methodology and discuss it in the limitations: conclusions are based on a subset of those "who reached the end," and that subset may differ from everyone who started. If you reduced drop-off through changes to the survey, give the dropout rate before and after — this shows how effective the improvements were. In SurveyNinja it is convenient to use data on incomplete and completed responses for each wave for this.

In short: the dropout rate shows the losses between "started" and "completed"; analyzing it by question gives you concrete points for improving the survey and raising the completion rate.

Dropout rate is the percentage of respondents who started a survey but did not complete it. It is related to the completion rate (dropout = 100% − completion) and to survey fatigue. Analyzing drop-off by question helps find problem spots and raise the completion rate. In SurveyNinja, the data for the calculation is available in reports and in the incomplete responses section.