Chapter 26

1) on page 92, ‘the trend adjusted for seasonal variations’ says: ‘ we could say that the trend has moved from 2702 to 2451 in 7 jumps , this is (2702-2451)/7=36/season.
I want to say that figure 2702 can not be found from the above diagram, just 2720 can be found. Meanwhiel, (2720-2451)/7=38/season, not 36.

Thank you. You are correct. It should have been 2720 and 38 per season

2) on page 93, ‘Exponential smoothing’, the prediction for Q3/Yr3
75%*2832+25%*2451=2736, the calculation based on last time’s actual resluts and last time’s predicted results.

But for the prediction for Q4/Yr 3,
75%*1920+25%*2737=2,124
according to the explanation of ‘exponential smoothing’, the predicted results should be based on the last last time’s actual resluts and last time’s predicted results.

I guess the prediction for Q4/Yr 3, should be:
75%*2160+25%*2737=2304.
Again, you are correct

Thank you for spotting these errors (you are the first person to comment in over a year!). We will change it as soon as we can