I would like to find or refer to the previous value in a time series so I can do a simple difference calculation between the current and the previous value.
The database i have has a date column, frequency, value. Each time series has different reporting frequency such as monthly, quarterly, yearly. I would like to be able to add another column in the database to show the prior value for the specific time series. Is this possible when the database has varying reporting frequencies?
Any help would be much appreciated