Homework 3 - This document is t it led "Homework...

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This document is titled “Homework 3” but will focus on the Ch. 7, EX 4. Moving average: For a four-period moving average, start with = + + + L4 D4 D3 D2 D14 ; this is the forecast for the demand of future periods until D5 is available. Then the formula is = + + + L5 D5 D4 D3 D24 . [I don’t see any real benefit for listing values of D in reverse order, but they are also arranged that way at http://en.wikipedia.org/wiki/Moving_average .] If the exercise only asked for the forecast of monthly demand for year 6, one could just compute =…= = = , + , + , + , = , F61 F72 L60 8 000 22 000 20 000 20 0004 17 500 . However, to decide how good the forecasts are, other computations are useful. Columns A through G make pretty good sense on the “moving average” worksheet, but instead of =SUM($F$6:F6)/(A6-4) for Cell H6 one could used =AVERAGE($F$6:F6). [For cell G6 I tried =AVERAGE($E$6^ 2:E6^ 2) but it didn’t support exponents.] The rest of the columns make sense, but the bias was requested and Figure 7-5 (the “template” for moving average) didn’t include it so Equation 7.25, = = Biasn t 1nEt is used for =SUM($E$6:E6) in Cell K6; column K is now used for bias instead of tracking signal, so instead of =SUM($E$6:E6)/H6 one can use = K6/H6. [It is obvious that TS 1 must be -1 or 1, but I haven’t figured out why following values are consecutive integers for moving average, simple exponential smoothing, and Holt’s model.] “ The vast majority of negative biases and the TS that are less than -6
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Homework 3 - This document is t it led "Homework...

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