I would use the database activity. You will have to set up the fields and the templates, but it will give you the most versatility. Depending on the age of your learners, you could brainstorm with them the fields they would need. Here is the documentation page which begins the database section. http://docs.moodle.org/23/en/Database_activity_module
After the study is completed, the data can be exported in CSV file which will open in Excel. That will allow you to do some formulas and build graphs from the data.