Question

Obtain trend values for the following data using 4-yearly centered moving averages.

Year	1971	1972	1973	1974	1975	1976
Production	1	0	1	2	3	2
Year	1977	1978	1979	1980	1981	1982
Production	3	6	5	1	4	10

Answer 1

Construct the following table for obtaining 4-yearly centered moving average for the data: 

Year t	Production yt	4–yearly moving total	4–yearly moving average	2 unit moving total	4–yearly centred moving averages trend value
1971	1
1972	0	4	1
1973	1	6	1.5	2.5	1.25
1974	2	8	2	3.5	1.75
1975	3	10	2.5	4.5	2.25
1976	2	14	3.5	6	3
1977	3	16	4	7.5	3.75
1978	6	15	3.75	7.75	3.875
1979	5	16	4	7.75	3.875
1980	1	20	5	9	4.5
1981	4	-	-	-	-
1982	10	-	-	-	-