Categories, Events, and Goals
A Category and an Event are pretty much the same, but an Event can have an action and must have a linked Category. An Event Log is the result of registering an Event at a certain time, either from the basic register window, or with the associated time elapsed in the pomodoro view.
The app also uses an ephemeral concept that does not exits in the database, Commitments, that it is used to track the goals during the current week.
Questionnaires
This model allows a questionnaire to have an arbitrary number of scales per questionnaire and question. We explicitly assume equal intervals between Likert-scale response options, which allow us to see our scales as a homogeneous discretization of an underlying continuum represented by a two-variable linear equation.
The classes below are a simplified version, the ones in the actual database of the app allow also to internationalize the questionnaires.
