Single-select matrix requirements
A single-select matrix in Pavlovia surveys can easily be set to require a single response or all responses, but custom response pattern requirements are also possible. In all cases the required toggle at the bottom of the question should be switched on.
All rows required
Tick Validation / Require answer for all rows
One row required
This is the default. Validation / Require answers for all rows is unticked but in this case I have added a custom “Required” error message
Some rows required
For this option I create a separate read-only expression question with the expression
{block_1/question3.1} notempty + {block_1/question3.2} notempty + {block_1/question3.3} notempty + {block_1/question3.4} notempty +
{block_1/question3.5} notempty + {block_1/question3.6} notempty + {block_1/question3.7} notempty + {block_1/question3.8} notempty +
{block_1/question3.9} notempty + {block_1/question3.10} notempty
In this demo the expression is visible. If you hide it remember to change “clear the value if the question becomes hidden” to None.
Then add a custom validation expression and error message such as {block_1/question4} > 4
This technique is most useful if the final entry of the single-select matrix is an Other option, which you want to be optional. In this case you could exclude that row from the expression question.