Question

Consider the following time series data.

Week	1	2	3	4	5	6
Value	18	12	15	10	18	14

Using the naïve method (most recent value) as the forecast for the next week, compute the following measures of forecast accuracy.

(a)	Mean absolute error
	If required, round your answer to one decimal place.
(b)	Mean squared error
	If required, round your answer to one decimal place.
(c)	Mean absolute percentage error
	If required, round your intermediate calculations and final answer to two decimal places.
(d)	What is the forecast for week 7?

Answer 1

Time period	Actual Value(A)	Moving avg. Forecast(F)	Forecast error E=|A-F|	Squared Forecast Error	|A-F|A
1	18
2	12	18	6	36	0.5000
3	15	12	3	9	0.2000
4	10	15	5	25	0.5000
5	18	10	8	64	0.4444
6	14	18	4	16	0.2857
7		14
		Total	26	150	1.93
		Average	5.20	30.00	38.60%
			MAD	MSE	MAPE

a) mean absolute error=			5.2
b) mean squared error =			30.0
c) mean absolute % error=			38.60%
d) forecast for week 7 =			14