ISyE 3103 Supply Chain Modeling: Transportation and Logistics
Spring 2006
Extra Time Series Extrapolation Forecasting Problems
These are extra problems1provided for those of you who would like some additional practice
in the mechanics of specifying time series extrapolation models. They will not count for any
credit in your homework grade, but completing them would undoubtedly be good prepara-
tion for the forecasting quiz and the exams.
Question 1 The following gives the number of pints of type A blood used at Woodlawn
hospital in the past six weeks.
WeekOf PintsUsed
August 31 360
September 7 389
September 14 410
September 21 381
September 28 368
October 5 374
1. Forecast the demand for the week of October 12 using a 3-week moving average.
2. Use a 3-week weighted moving average with weights of 0.1, 0.3, and 0.6. Use 0.6 for
the most recent demand observation. Forecast the demand for the week of October 12.
3. Compute the forecast for the week of October 12 using exponential smoothing with a
forecast for August 31 of 360 and α= 0.2.
Question 2 Income at the law firm of Smith and Wesson2for the period from February
to July was as follows:
Month Income(in000s)
February 70.0
March 68.5
April 64.8
May 71.7
June 71.3
July 72.8
1. Use Holt’s Method (Double Exponential Smoothing) to forecast the law firm’s August
income. Assume that the initial parameter estimates are ˆa0= 65 and ˆ
b0= 0, and use
smoothing parameters α= 0.1 and β= 0.2.
2. Repeat the above using smoothing parameters α= 0.2 and β= 0.1.
1All of these problems are from Chapter 4 of the 6th edition of Principles of Operations Management by
Heizer and Render published in 2006.
2How corny is that!
