311 Operations Management
Spring 2009
Homework 4: Forecasting
Due March 26, 2009
1.
(20 points; 10 points per part) a. Calculate the value of
α
for exponential smoothing
that is equivalent to a weekly moving average over a period of two years (N=52*2=104)
2/(104+1) = .019 =
α
b. What time units would the value of
α
=.15384615 as an exponential smoothing constant
roughly translate into when evaluating a moving average over a year (Hint: Calculate the
value of N and decide the how a year would be broken up as a result)?
(2/.15384615)1 = 12 = N, 12 periods in a year = months
2.
(20 points; 10 points per part)
Problem 9, parts a and b on page 507 in the textbook.
a.
567
b.
460
3.
(40 points; 10 points part a, 20 points part b, 10 points for correct MAD for each
forecast is 20 points total for part c)
Problem 14, parts a, b, and c, on page 508 in the
textbook.
a  c.
Month Demand
Exponential
smoothing
Absolute
deviation
T
t
F
t
FIT
t
Absolute
deviation
1
31
31.00
1.00 30.00 31.00
2
34
31.00
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 Fall '07
 Vaitsos
 Management, Normal Distribution, Standard Deviation, Mean

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