Choice Filters

Cascading Selects are a special case of choice filters where the choices for a select question are dependent only on a single previously asked select question. However choice filters can be much more flexible and powerful with rules being used to identify choices that should be displayed that are dependent on the answers to many other previously answered questions. Because of this flexibility the online editor takes a similar approach to that used by the spreadsheet editor so rather than using a point and click interface:

A choice filter rule is specified that can refer to previously answered
questions and also to codes associated with each choice.  If the rule evaluates as
true for a choice then that choice is shown.

This means that you can do anything in the online editor that you can do in the spreadsheet editor but that you may need some specialist knowledge.

In the following diagram a choice filter is specified so that a question on favourite fruit only include choices selected by a user for a question on which fruit they liked.

Choices being specified using Online choice Filter

• "Custom Filter" has been selected from the filter drop down
• A choice filter rule has been specified (1)
• The Add Filter Column button (2) has been clicked once to create a filter column called "liked"
• Codes have been entered into the filter column(3)

An explanation of the choice filter rule:

selected(${fruit_liked}, liked)
${fruit_liked} refers to the answer to the fruit_liked question
liked, without the ${} syntax refers to the filter column.
So this means that any choice that has a value in the liked column that was selected
in the fruit_liked question will be shown

Deleting a filter column

As you can see in the above picture there is an "Add Filter Column" button but no "Delete Filter Column" button. Instead to delete a filter column you have to delete all of the values for that column.