Question

Obtain 4 yearly centered moving averages for the following time series:

Years	1981	1982	1983	1984	1985	1986	1987	1988	1989	1990	1991
Number of crime ('000)	40	42	43	42	44	44	43	46	47	45	46

Answer 1

Years	Xi	4-yearly moving total	4-yearly moving average	2-unit moving total	4-yearly centered average moving (trend value)
1981	40
1982	42	167	41.75
1983	43	171	42.75	84.5	42.25
1984	42	173	43.25	86.0	43.00
1985	44	173	43.25	86.5	43.25
1986	44	177	44.25	87.5	43.75
1987	43	180	45.00	89.25	44.625
1988	46	181	45.25	90.25	45.125
1989	47	184	46.00	91.25	45.625
1990	45
1991	46