Errata Updates to “Principles of Business Forecasting” By Ord and Fildes
After Chapters 3 and 4 were completed, the Exponential Smoothing Macro [ESM] was developed. The ESM is more comprehensive and more flexible than the macros developed earlier and cited in the text [SES.xlsm, LES.xlsm, HW_quarterly.xlsm and HW_monthly.xlsm]. Thus, wherever one of these earlier macros is mentioned, the reader should use the ESM instead. The ESM is described in detail in the website materials; Appendices 3A and 4A may be ignored.
NOTE: The solutions on the website are not in general meant to be a complete answer to the question posed (particularly for the more complex cases). Some of the solutions have not yet been posted. If you have queries or improvements to suggest, please contact one of the authors.
OTHER CHANGES
Page 7, section 1.3.1. Definitions for Trend and Seasonal should be provided at this stage. For consistency with later discussions (pages 74 and 100 respectively) we recommend the following:
Trend: A time series is said to have a trend if the mean level at any point in time is expected to change, relative to past values. Such trends may be linear, exponential or evolve in a local fashion.
Seasonal: A time series is said to have a seasonal component if it displays a recurrent pattern with a fixed and known duration (e.g. by days of the week or months of the year)
In presenting the introductory material in chapters 1 and 2 we found the following amended and new slides useful
Page 59: We now provide a single Excel macro, the Exponential Smoothing Macro (ESM) along with a complete guide, ESM Manual, on the book’s website. All later references to exponential smoothing macros should be taken to refer to the ESM; see, for example, the first sentence in section 3.3.2 on page 69, the footnote on page 73 and the end-of-chapter Exercises for Chapters 3 and 4.
Page 70, Table 3.4: The entries in columns SES (0.5) and SES (opt) are incorrect. Delete the first entry in each column and move the remaining entries up by one row. In the last row (period 36) add the entries 32409 and 31739 respectively. Figure 3.7 is similarly affected. The corrected table and figure are provided below.
Table 3.4: Actual and one-step-ahead forecasts for WFJ Sales for periods 27–36, starting from period 26 as origin and using SES.xlsm
Period / WFJ Sales / SES (0.2) / SES (0.5) / SES (opt)27 / 30,986 / 33,884 / 34,346 / 34,580
28 / 33,321 / 33,304 / 32,666 / 31,963
29 / 34,003 / 33,308 / 32,993 / 32,952
30 / 35,417 / 33,447 / 33,498 / 33,717
31 / 33,822 / 33,841 / 34,458 / 34,955
32 / 32,723 / 33,837 / 34,140 / 34,130
33 / 34,925 / 33,614 / 33,432 / 33,105
34 / 33,460 / 33,876 / 34,178 / 34,431
35 / 30,999 / 33,793 / 33,819 / 33,723
36 / 31,286 / 33,234 / 32409 / 31739
Page 73, footnote 5: The cross-reference should be to Chapter 9, section 9.6.1.
Page 88: The ESM allows values of c in the range with c=0 defaulting to the log transform.
p. 93: Exercise 3.7 should read 1989, not 1990
p. 93: Exercise 3.0 should read Netflix_1 not Netflix
Page 94, Minicase 3.2: The cross-reference in the first line should be to Minicase 2.2, not Table 2.11.
p. 95: Table 3.20 uses Netflix.xlsx not Netflix_2.xlsx
Page 97, Appendix 3A: Ignore this material and use the ESM Guide, available on the book website.
p. 104: The file SES_12_months is now included in Data Sets
p. 114: Table 4.5B is now included in Examples_chapter_4.xlsx
p. 122: The file Exercise_4_2.xlsx is now included in Data Sets
Page 126, Appendix 4A: Ignore this material and use the ESM Guide, available on the book website.
Pages 143-144: The cross-references to earlier exercises in Exercises 5.2 and 5.3 should be to Exercises 3.1, 3.3 and 3.2, 3.5 respectively and not to items in Chapter 4.
p. 144: Exercise 5.9 should refer back to Minicase 4.1, not 5.1
Page 144, Exercise 5.9: The cross-references should be to Minicase 2.2 (not Table 2.11) and Minicase 4.1 (not 5.1).
In chapter 8 the residuals slide should be amended as follows:
The outline solution to mini-case 8.5 has been extended.
There is a minor correction to slide 9.5.2 as follows:
Ord/Fildes Principles of Business Forecasting 1e Errata Sheet • September 2014