Underneath the Time stamp drop-down box is a drop-down box that allows the user to specify the Periodicity of the data. If a date field has been selected as the time stamp, then the system can use heuristics to automatically detect the periodicity - "" will be set as the default if the system has found and set a date attribute as the time stamp initially. If the time stamp is not a date, then the user can explicitly tell the system what the periodicity is or select "" if it is not known. Periodicity is used to set reasonable defaults for the creation of lagged variables (covered below in the Advanced Configuration section). In the case where the time stamp is a date, Periodicity is also used to create a default set of fields derived from the date. E.g. for a monthly periodicity, month of the year and quarter fields are automatically created.