� = 12 × 903,57
− 78 × 138,34 12 × 650
− 78
2
= −0,030206
ln � =
∑ ��� − � ∑ � �
= 11,33259 � = 83.499,2
�
′
= ��
��
�
′
= 83.499,2 �
−0,0302065 �
�
′
= 83.499,2 �
−0,0302065 1
= 86.059,85 ≈ 86.060
���� =
∑ |
��
�
|
� �=1
�
=
2,69 12
= 22,42
2. Metode Siklis
Jumlah periode adalah: � =
12 3
= 4
SIKLIS t
Y Sin2πtn Cos2πtn
Sin 2πtnCos
2πtn Sin2
2πtn Cos2
2πtn YSin2πtn YCos2πtn
1 80786
1,000 0,000
0,000 1,000
0,000 80786,25
2 58149
0,000 -1,000
0,000 0,000
1,000 0,00
-58149
3 124014
-1,000 0,000
0,000 1,000
0,000 -124014,00
4
76981 0,000
1,000 0,000
0,000 1,000
0,00 76980,5
5 96601
1,000 0,000
0,000 1,000
0,000 96600,75
6 137403
0,000 -1,000
0,000 0,000
1,000 0,00
-137402,5
7 113036
-1,000 0,000
0,000 1,000
0,000 -113035,50
8
142224 0,000
1,000 0,000
0,000 1,000
0,00 142224
9 111110
1,000 0,000
0,000 1,000
0,000 111110,00
10 115477
0,000 -1,000
0,000 0,000
1,000 0,00
-115476,75
11 145007
-1,000 0,000
0,000 1,000
0,000 -145006,75
12
68058 0,000
1,000 0,000
0,000 1,000
0,00 68058,25
78 1.268.844
6 6
-93559,25 -23765,5
Universitas Sumatera Utara
∑ y = t a + b
∑ sin�
2 πt
n
� + c ∑ cos�
2 πt
n
� 1.268.844
= 12 a + b 0 + c 0 a
=
1.268 .844 12
a = 105.737,02
∑ y sin�
2 πt
n
� =a
∑ sin�
2 πt
n
� + b ∑ sin
2
�
2 πt
n
�+ c ∑ sin�
2 πt
n
�cos�
2 πt
n
� -48.237,499
= 95.540,833 0 + b 4 + c 0 b
=
−93.559,25 4
b = -23.389,81
∑ y cos �
2 πt
n
� = a
∑ cos �
2 πt
n
�+ c ∑ cos
2
�
2 πt
n
�+ b ∑ sin�
2 πt
n
�cos�
2 πt
n
� 26.455
= 95.540,833 0 + c 4 + -8.222,778 0 c
=
−23.765,5 4
c = -5.941,375
y’= a + b sin �
2 πt
n
�+ c�
2 πt
n
� y’= 105.737,02 – 23.389,81 sin
�
2 πt
n
� - 5.941,375 cos �
2 πt
n
� y’= 105.737,02 – 23.389,81 sin
0,866 - 5.941,375 co �−0,500 = 82.347,208
���� =
∑ |
��
�
|
� �=1
�
=
2,92 12
= 24,34
Metode Terpilih: Eksponensial
Universitas Sumatera Utara
Verifikasi Peramalan
y yt
e=y-yt |MR|
UCL LCL
80.786 86.060
-5.274 -
93.883,39 -93.883,39
58.149 88.699
-30.550 25.276,42
93.883,39 -93.883,39
124.014 91.419
32.595 63.144,89
93.883,39 -93.883,39
76.981
94.223
-17.242 49.837,02
93.883,39 -93.883,39
96.601 97.112
-511 16.730,75
93.883,39 -93.883,39
137.403 100.090
37.312 37.823,64
93.883,39 -93.883,39
113.036 103.160
9.876 27.436,44
93.883,39 -93.883,39
142.224
106.323
35.901 26.024,93
93.883,39 -93.883,39
111.110 109.584
1.526 34.374,58
93.883,39 -93.883,39
115.477 112.944
2.532 1.006,18
93.883,39 -93.883,39
145.007 116.408
28.599 26.066,37
93.883,39 -93.883,39
68.058
119.978
-51.920 80.518,35
93.883,39 -93.883,39
388.239,58
-150.000 -100.000
-50.000 50.000
100.000 150.000
Jan u
ar i
F e
b ru
a ri
M a
re t
A p
ri l
M e
i Ju
n i
Ju li
A g
u st
u s
S e
p te
m b
e r
O k
to b
e r
N o
v e
m b
e r
D e
se m
b e
r P
T .
JW L
Peramalan Irawan 684-S tahun 2016
Irawan 684-S LCL
UCL
Universitas Sumatera Utara
PERAMALAN PRODUK IRAWAN 9001 – PT. SWMS
Irawan 9001 Bulan
Demand Januari
5.817
Februari 4.753
Maret
9.034
April 7.028
Mei 8.577
Juni 4.028
Juli
5.656
Agustus 7.888
September 7.520
Oktober 6.012
November 5.014
Desember
4.760
Total 76085
Metode Peramalan Terpilih: •
Metode Kuadratis •