Method 1: Last Year to This Year

This table is history used in the calculation of MAD, given Periods of Best Fit = 5:

Past Year	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
2	None	None	None	None	None	None	None	128	118	123	139	133

This table is the 110 Percent Over Last Year forecast for the Holdout Period:

Past Year	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
1	None	None	None	None	None	None	None	141	130	135	153	146

This table is the Actual Sales History for the Holdout Period:

Past Year	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
1	None	None	None	None	None	None	None	129	131	114	119	137

This table is the Absolute Value of Errors, (Actual) – (Forecast):

Past Year	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
1	None	None	None	None	None	None	None	12	1	21	34	9

Mean Absolute Deviation = (12 + 1 + 21 + 34 + 9) / 5 = 15.4