Survey Usage

No they can simply close the tab. They restart the survey where they left off using the same link. 

Ok, thanks

Just be sure to check your Incomplete Responses settings in the settings for the survey you’re working in. You should be able to choose how long is allowed between survey start & when it is recorded as incomplete!

ok, thanks

In the survey, you can set how long the link remains active after a respondent starts it. During this time, respondents can close the window and later resume the survey from where they left off.

This will help you understand on the basis of distribution as well - 

• Anonymous Links: When respondents access a survey through an anonymous link, Qualtrics stores their progress using a browser cookie. If they close the survey and later reopen the same link in the same browser, they can continue from where they left off.
• Email or SMS Distributions: For surveys distributed through personalized email or SMS links, progress is automatically associated with the respondent's unique link. This allows them to resume the survey from any browser or device, provided they use the original link they received.

You can change the “Next” button text to “Save and close” this will give them feeling that they can return later to restart from where they are leaving.