These periods depend on the type of current analysis period. On a daily basis the default period is set to Day-7 so that a comparison can be made with the same day a week earlier. The different periods can be accessed directly from the Calendar. Relevant comparison periods are also displayed. For example, a 3-day week or 3-day month (in other words an unfinished week/month) will be compared to the first 3 days of the previous week or previous month. It will not be compared to the previous week/month in its entirety (which would imply a systematic decrease for the beginning of the week, month or year).