If Skip Logic has been applied to the design, then your logic is most likely skipping respondents over sections or pages containing required questions.
Check the survey to confirm what questions/pages have logic and which page it is jumping respondents over.
- Begin in the Analyze section by selecting to view all pages. (That option is located in the upper left side of the Response Summary page, to the right of the left sidebar.)
- Any respondent that has been jumped according to the logic will have blank pages. If the respondent was never directed to that page, then that respondent was never able to answer those questions.
- Pages further along in the design will have their answers on the questions if the respondent was directed to them.
If instead a person just exited early, the rest of his/her response will be blank when viewing the survey.