I am trying to link the volume sold on a service to the price of it. However, the timing differs as the service gets paid months in advance. Consequently, a lag is required.

However, as my data on volume starts on Januar 2005 (first row), I need price data from 2004 (e.g. October 2004 for price and January 2005 for volume in case of a 3 months time lag).

I am thinking about creating a new variable (call it 3mLag or so), where I simply move the pricing data by 3 lines (copy paste) while putting in the missing data for 2004.

Is there probably a faster way that may help as my procedure is only simple in case of a small number of lags to be implemented?