Forecasting Average Monthly Growth Rates

[H7H12]

Hi there, I have a simple forecasting query that I'm struggling to solve. Hoping you can help! I wish to forecast a target monthly growth rate, based on 12 months worth of data, for example:


Date|Visits
Dec-11|1000
Jan-12|1200
Feb-12|900
Mar-12|800
Apr-12|900
May-12|1000
Jun-12|720
Jul-12|450
Aug-12|230
Sep-12|101
Oct-12|156
Nov-12|1000
Dec-12|2031




The method I have tried so far are (if Jan-12 is A3, Visits amount Jan-12 is B3 and Dec-11 are A2 & B3 respectively):


B3-B2/ABS(B2)


Performing this calculation for all months then averaging the results.


I am concerned I am not forecasting a target growth rate in the optimum way. I have experimented with using Excel's more advanced forecasting, but I'm not sure such detail is necessary. I simply want to be able to say 'aim for a 2% growth rate', for example.


Any input you can offer would be much appreciated. I am on Windows XP using Excel 2007.

 

[xenou]

your data is very erratic. You could plot the same visits each month with a 2% increase in each month. The average is a little over 800 visits a month but it's hard to say if it would be meaningful to project that number for each month - maybe just look at that as a target for the final YTD number. I don't see growth month to month as helping you here - given how it goes way up and way down depending on the month it won't be very useful for projections unless you have reason to think that the monthly variation repeats each year in a consistent way (seasonality).