Seasonal Variation Factors Based On A Centered Moving Average - HP 12c Solutions Handbook

Simple Moving Average
• X = moving average.
• m = number of elements in moving average.
•
X
1
X = ------------------------------------------------------ -
1
•
X +
1
X = ---------------------------------------------------------------- -
2
• etc.

Seasonal Variation Factors Based on a Centered Moving Average

• X = centered moving average
c
• m = number of elements in the centered moving average.
•
X
1
------
2
X = -------------------------------------------------------------------------------------- -
c
• SV = Seasonal variation factor.
• x = value of the ith data point.
i
• i = centered moving average of the ith data point.
•
X
i
SV = ---- -
X
i
Gompertz Curve Trend Analysis
(bx)
• y = ca
• where x, y, a, b, and c are positive.
•
S
–

3
------------------ -
b =

S
–
2
...x
+ X + X + X
2 3
m
m
nm
m
...x
X + X + X +
2 3
m
m
nm
m
...x
+ X + X + X MM
m
2 3
m
1
-- -
S
n

2

S
1
1
X + 1
m
+ -----------------
2
1 a –
D t = S t + ---------------- - T t
155