When you add a checkbox question to your survey, you may want to limit the number of choices that one can choose. Using this option, you can require the respondent to choose a certain number (or range) of choices. For example, you may have a list of 20 different movies and want to ask respondents to choose between 2-5 movies from the list. With this option in checkbox questions, such validation controls can be placed with ease.
How to Use:
Once you add a checkbox matrix to your survey, you can click on the “Choice Restriction” option on the Options tab of the Control Panel to reveal the extra options. In the new textboxes that appear, you can specify a range of choices that the end user can choose.
Watch this video tutorial on checkbox question types: