Please help me solve this problem... Thank you. Problem: GB Computer Services re
ID: 3042682 • Letter: P
Question
Please help me solve this problem... Thank you.
Problem:
GB Computer Services repairs and services personal computer at its store, and it makes local service calls. It primarily uses part-time university students as technicians. The firm has had a steady growth since it started. Managers purchase generic computer parts in volume at a discount from variety of sources whenever they see a good deal. Thus, they need a good forecast of demand for repairs so that they will know how many computer component parts to purchase and stock, and how many technicians to hire.
The company has accumulated the demand data shown in the table below for repair and service calls for the past 12 months, from which it did consider simple exponential smoothing using a smoothing constant alpha = 0.3, and using the demand of period 1 as both demand and forecast for period 1 (i.e. F1 = A1)
Period
Month
Demand for Repair and Service Calls
Forecast
1
January
37
2
February
40
37.000
3
March
41
37.900
4
April
37
38.830
5
May
45
38.281
6
June
50
40.297
7
July
43
43.208
8
August
47
43.145
9
September
56
44.302
10
October
52
47.811
11
November
55
49.068
12
December
54
50.848
a) Construct a Control Chart to monitor the forecast accuracy using control limits of ± 3 (i.e. = standard deviation). Show your work.
b) Is the forecast performing adequately? Explain.
Period
Month
Demand for Repair and Service Calls
Forecast
1
January
37
2
February
40
37.000
3
March
41
37.900
4
April
37
38.830
5
May
45
38.281
6
June
50
40.297
7
July
43
43.208
8
August
47
43.145
9
September
56
44.302
10
October
52
47.811
11
November
55
49.068
12
December
54
50.848
Explanation / Answer
Month Actual demand Forecast Jan 37 Feb 40 37 Mar 41 37.9 Apr 37 38.83 May 45 38.281 Jun 50 40.297 Jul 43 43.208 Aug 47 43.415 Sep 56 44.302 Oct 52 47.811 Nov 55 49.068 Dec 54 50.848 Mean 46.42 Sigma 6.93 UCL 67.22 Mean +3*Sigma LCL 25.61 Mean -3*Sigma As we see that all the forecast values are within the control limits so it is under control