160 Appendix B
Forecasting
Simple Moving Average
average. moving x =
average. movingin elements ofnumber
=m
m
xxxx
x
m
++++
=
...
321
1
m
xxxx
x
m 1432
2
...
−
++++
=
etc.
Seasonal Variation Factors Based on a Centered Moving Average
average moving centered
c
=x
m = number of elements in the centered moving average.
()
m
x
xxx
x
x
m
m
c
2
...
2
1
32
1
+
+++++
=
SV = Seasonal variation factor.
x
i
= value of the ith data point.
point. datath theof average moving centered ix
i
=
i
i
x
x
SV
=
Gompertz Curve Trend Analysis
x
b
cay =
where x, y, a, b, and c are positive.
n
SS
SS
b
/1
12
23
−
−
=
−+
−
=
231
2
231
2
1
exp
SSS
SSS
n
c
()( )
()
−
−−
=
2
12
1
1
exp
n
bb
SSb
a
where S
1
, S
2
, and S
3
are:
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