The following example shows the calculation of the demand estimation for month 24 concerning a part with the following history:

History of Months/Demand - Month 24 is the current month

Months

Demand

Months

Demand

1

100

13

200

2

200

14

300

3

300

15

400

4

200

16

300

5

100

17

300

6

200

18

400

7

300

19

500

8

200

20

400

9

100

21

400

10

200

22

500

11

300

23

600

12

200

24

?


To prepare the estimation for the month 24, you simulate the months 21, 22, 23 do not exist, apply the formulas to estimate the demand of these periods, and identify the formula that adheres to this situation the most.

Thus, you obtain the following results for each formula:

Note: D = Demand = aConsumo


Stability

D21=D20+400  Error = 0%

D22=D21+400  Error = -20%

D23=D22+500  Error = -16,70%


Formula accumulated error  = -36,7%


Average  (Last three months)

D21=(D18+D19+D20)/3 = 433 Error =   8,3%

D22=(D19+D20+D21)/3 = 433 Error = -13,4%

D23=(D20+D21+D22)/3 = 433 Error = -27,8%


Formula accumulated error = -32,9%


Tendency

D21 = D20+(D20-D19) = 300 Error = -25%

D22 = D21+(D21-D20) = 400 Error = -20%

D23 = D22+(D22-D21) = 600 Error =   0%


Formula accumulated error = -45%



Seasonality

 




Formula accumulated error = -36.6%