Unit 6 Assignment (Read Carefully)
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GB513 UNIT 5 SUCCESS GUIDE
GB 513 SUPPORT MATERIALS
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UNIT 5 SUCCESS GUIDE
1. As always, start by reading the chapters and studying the solved examples.
2. Watch my lecture video on forecasting in Course Documents. It is a comprehensive
video explaining just about everything in the assignment-moving averages, calculating
the errors, forecasting using graphs.
3. Watch the sample problem solutions in Course Documents.
4. If you want to see more videos on how to fit trendlines in scatter graphs (for problem #3)
watch this: http://www.youtube.com/watch?v=6rOlGbLeQxI.
5. If you want more on moving averages then:
http://www.youtube.com/watch?v=FQE6BdDRtnk
6. If you want more on calculating the errors: http://www.youtube.com/watch?v=iRoEOU-
YYaU
Avoid these mistakes!
Problem 3 should be done using a scatter graph and fitted trend-lines. Some students try
to do multiple regression, which is a more complex and unnecessary way.
The questions below are very similar to what you need to solve in the Assignment.
Some, but not all, of these solutions were demonstrated on video and recorded
for the live binder by the math tutors.
SAMPLE PROBLEM 1 FOR ASSI GNMENT PROBLEM 1 Using the following data, determine the values of MAD and MSE. Which of these measurements
of error seems to yield the best information about the forecasts? Why?
Period Value Forecast
1 19.4 16.6
2 23.6 19.1
3 24.0 22.0
RESOURCES
COMMON MISTAKES IN THE ASSIGNMENT
SAMPLE PROBLEMS AND SOLUTIONS
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Solution
Period Value F e e2
Total 21.5 21.5 94.59
MAD = 21.5/6 = 3.583
MSE = 94.59/6 = 15.765
4 26.8 24.8
5 29.2 25.9
6 35.5 28.6
1 19.4 16.6 2.8 2.8 7.84
2 23.6 19.1 4.5 4.5 20.25
3 24.0 22.0 2.0 2.0 4.00
4 26.8 24.8 2.0 2.0 4.00
5 29.2 25.9 3.3 3.3 10.89
6 35.5 28.6 6.9 6.9 47.61
SAMPLE PROBLEM 1 FOR ASSIGNMENT PROBLEM 2 Please note that my lecture video covers this problem step by step.
Use the following time‐series data to answer the given questions.
Time Period Value Time Period Value
1 27 6 66
2 31 7 71
3 58 8 86
4 63 9 101
5 59 10 97
a. Develop forecasts for periods 5 through 10 using 4‐month moving averages.
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SOLUTION
a.)
4‐mo. mov. avg. error
b. Develop forecasts for periods 5 through 10 using 4‐month weighted moving averages. Weight
the most recent month by a factor of 4, the previous month by 2, and the other months by 1.
44.75 14.25
52.75 13.25
61.50 9.50
64.75 21.25
70.50 30.50
81.00 16.00
b.) 4‐mo. wt. mov. avg. error
53.25 5.75
56.375 9.625
62.875 8.125
67.25 18.75
76.375 24.625
89.125 7.875
c.) difference in errors
14.25 ‐ 5.75 = 8.5
3.626
1.375
2.5
5.875
8.125
In each time period, the four‐month moving average produces greater errors of forecast.
than the four‐month weighted moving average.
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SAMPLE PROBLEM 1 FOR ASSI GNMENT PROBLEM 3 The forecasting video demonstrates how to fit trendlines to scatter graphs.
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Resources
Corman, L. (2010, September 28). Trend lines and regression analysis in excel. Retrieved
from https://www.youtube.com/watch?v=6rOlGbLeQxI
East Tennessee State University. (2012, September 13). MAD and MSE calculations. Retrieved
from https://www.youtube.com/watch?v=iRoEOU-YYaU
East Tennessee State University. (2012, September 13). Weighted moving average.
Retrieved from https://www.youtube.com/watch?v=FQE6BdDRtnk