What is Moving Average?
It is technique use to calculate the overall trend with the help
of historical data. To calculate the moving average simply calculates the
average of set of data with time period. There are 4 type of Moving Average
that is:
·
Simple Moving Average
·
Cumulative Moving Average
·
Weighted Moving Average
·
Exponential Moving Average
Example: Find
out the simple moving average of following year sales data of XYZ Company by
using 3 moving years
Year |
Sales (Rs.) |
1 |
5259 |
2 |
6453 |
3 |
9845 |
4 |
4865 |
5 |
3212 |
6 |
9856 |
7 |
4578 |
8 |
5965 |
Solution:
Year |
Sales (Rs.) |
Moving Average (for 3 years) |
Deviation |
Absolute Deviation |
Squared deviation |
Absolute Percentage Error |
1 |
5259 |
|
|
|
|
|
2 |
6453 |
|
|
|
|
|
3 |
9845 |
(5259+6453+9845)/3 =7185.67 |
2659.33 |
2659.33 |
7072054 |
0.27012 |
4 |
4865 |
(6453+9845+4865)/3
=7054.33 |
-2189.33 |
2189.33 |
4793180 |
0.450017 |
5 |
3212 |
(9845+4865+3212)/3 =5974 |
-2762.00 |
2762.00 |
7628644 |
0.8599 |
6 |
9856 |
(4865+3212+9856)/3
=5977.67 |
3878.33 |
3878.33 |
15041469 |
0.3935 |
7 |
4578 |
(3212+9856+4578)/3 =5882 |
-1304.00 |
1304.00 |
1700416 |
0.284841 |
8 |
5965 |
(9856+4578+5965)/3
=6799.67 |
-834.67 |
834.67 |
696668 |
0.139927 |
|
Total |
|
|
13627.67 |
36932432 |
2.398305 |
Deviation
= Actual sales-Forecast (Moving average)
Absolute
deviation =Ignore minus sign
Squared deviation = Absolute deviation ^2
MAD
= Ʃ ǀ actual –forecast ǀ / n
=13627.67/6
=2271.28
MSE = Ʃ (forecast errors) 2 / n
=36932432/6
=6155405.33
MAPE = 100* Ʃ ǀ actual i –forecast i ǀ/actual i /
n
=2.398/6
=0.3996
Example: Find out the next year forecasted sales by using weighted
moving average with the help of given information
Year |
Sales |
2012 |
49 |
2013 |
45 |
2014 |
32 |
2015 |
25 |
2016 |
28 |
The weights are 0.6, 0.2
and 0.2
Solution:
|
A |
B |
C |
D |
1 |
Year |
Sales |
Weighted Moving Average |
Formula |
2 |
2012 |
49 |
|
|
3 |
2013 |
45 |
|
|
4 |
2014 |
32 |
|
|
5 |
2015 |
25 |
38 |
0.6*B4+0.2*B3+0.2*B2 |
6 |
2016 |
28 |
30.4 |
0.6*B5+0.2*B4+0.2*B3 |
7 |
2017 |
30 |
28.2 |
0.6*B6+0.2*B5+0.2*B4 |
8 |
2018 |
21 |
28.6 |
0.6*B7+0.2*B6+0.2*B5 |
9 |
2019 |
|
24.2 |
0.6*B8+0.2*B7+0.2*B6 |
Highest Weight is given to recent sales price and less weight is given to last year to calculate average.
Example:
Find out the MAD and MSE of given information:
Year |
Demand |
2015 |
40 |
2016 |
35 |
2017 |
38 |
2018 |
42 |
2019 |
55 |
Weights are 0.5 and 0.3.
Solution:
|
A |
B |
C |
D |
E |
F |
1 |
Year |
Demand |
Weighted Moving Average |
Formula |
Deviation |
Squared deviation |
2 |
2015 |
40 |
|
|
|
|
3 |
2016 |
35 |
|
|
|
|
4 |
2017 |
38 |
14.75 |
(0.5*B3+0.3*B2)/2 |
23.25 |
540.56 |
5 |
2018 |
42 |
14.75 |
(0.5*B4+0.3*B3)/2 |
27.25 |
742.56 |
6 |
2019 |
55 |
16.2 |
(0.5*B5+0.3*B4)/2 |
38.8 |
1505.44 |
7 |
2020 |
59 |
20.05 |
(0.5*B6+0.3*B5)/2 |
38.95 |
1517.10 |
8 |
2021 |
37 |
23 |
(0.5*B7+0.3*B6)/2 |
14 |
196 |
|
Total |
|
|
|
142.25 |
4501.67 |
MAD = Ʃ ǀ actual –forecast ǀ
/ n
=142.25/5
=28.45
MSE = Ʃ (forecast
errors) 2 / n
= 4501.67/5
=900.34
Example:
Find out the next month sales with the help information:
·
Using
Exponential Moving Average
·
Sales of 6
months are given as
· Alpha is 0.2
Month |
Sales |
EMA |
Jan |
88 |
38 |
Feb |
98 |
? |
March |
94 |
? |
April |
75 |
? |
May |
86 |
? |
June |
80 |
? |
Solution:
Month |
Sales |
Exponential Moving Average |
Jan |
88 |
68 |
Feb |
98 |
72 |
March |
94 |
77.2 |
April |
75 |
80.56 |
May |
86 |
79.45 |
June |
80 |
80.76 |
St=α*(Yt-1)
+ (1-α)*St-1
Where,
St=
EMA
α= alpha*
(Yt-1)
= Sales of previous period
St-1
= EMA previous period
S Feb = 0.2*88 + (1-0.2)*68
= 17.6+0.8*68
=17.6+54.4
Feb=72
=0.2*98+ (1-0.2)*72
=19.6 + 0.8*72
= 19.6 + 57.6
March=77.2
=0.2*94+ (1-0.2)*77.2
= 18.8 + 0.8*77.2
= 18.8 + 61.76
April=80.56
=0.2*75+ (1-0.2)*80.56
=15 + 64.45
May=79.45
=0.2*86 + (1-0.2)*79.45
=17.2 + 63.56
June= 80.76
Comments
Post a Comment