It is possible to set mandatory questions.

I'm wondering if it is possible to require that a certain percentage, let's say 50%, of questions of the current group to be answered. (not matter which questions are answered)


Thanks

No, not without JavaScript manipulation and that would depend on the question types.

I think you can use a Short text question type. And for example , if you have 6 question Q1 to Q6, set
www.limesurvey.org/manual/Question_type_...28em_validation_q.29

to
Set the tip : you must answer to more than 3 question in this group, and create a class for example 'hidden-answer' to hide the answer part of this question.
Or maybe better : "show-only-tip" where you can hide whole but shown only the tip.

PS : related feature request : bugs.limesurvey.org/view.php?id=8885

@DenisChenu, yes, that's a valid workaround.

However, I find that my customers prefer to have the "Next" button disabled (with a warning element) until the required question(s) are completed.

This, of course, requires a little JS that could be circumvented, but they are aware of that risk and opt for it anyway. In the 7-8 years I have used this type of workaround, I have not had any reports of "cheating".

I like to do the 2 part :
- Expression Manager : diable system in PHP too : no way to submit invalid survey
- Javascript : better and speediest way to show it at user

Even better.

(in fact : i do the EM and search on LimeSurvey forum post from tpartner for the javascript workaround )