This tutorial demonstrates how you can use a Branch Node to branch participants based on a score within a questionnaire. This example includes an informed consent questionnaire. Participants should only continue with the experiment if they consent to all items in the questionnaire. If participants do not consent to all items, they should be rejected from the experiment.
Within the consent form questionnaire, the Multiple Choice Grid is used to present three statements for participants to agree to. As there are multiple statements, the easiest way to evaluate whether participants have consented to all three, is by creating a questionnaire score.
First, you need to create a score within the scoring tab. In this example, the score is called ConsentScore. Then, you need to choose which questions should be included within the score. Here, the consent question has been included and the default scoring mode has been selected. This means that if the statement within the question is ticked, a score of 1 will be received. If left unticked, a score of 0 will be received. Therefore, if participants consent to all three consent statements within this question, the final ConsentScore value will be 3.
Scores within a questionnaire are automatically saved to the Store. This means that the score can be used within the Branch node in the experiment tree to divide participants into 2 groups: those who consented to all statements, and those who did not.
For the consent group within the Branch node, the Store field setting (or Property setting, if you're using Classic Experiment Builder) is set to ConsentScore to match the name of the score within the questionnaire. This allows Gorilla to correctly identify the value to be evaluated. Participants only consented to all statements if the value in the ConsentScore is equal to 3. Participants who meet this criteria can continue with the rest of the experiment.
Then, the non-consent group is set as the Default. This means that any participants who do not meet the criteria of the consent group will be automatically assigned to the non-consent group as they did not agree to all of the statements. These participants are rejected from the experiment via the Reject node.
This tutorial shows the new Experiment Builder interface. If you’re still using the classic interface, it will appear slightly different. In particular, the 'Store field' setting on the Branch Node is called 'Property' in Classic Experiment Builder.
