Forecasting techniques - numerical questions
Maze Green Yachts plc
Maze Green has been in business selling yachts and other pleasure craft for the last 14 years. Their sales record is reproduced below:
Year | Quarter | Yacht sales |
---|---|---|
2008 | 1 | 6 |
2 | 10 | |
3 | 12 | |
4 | 8 | |
2009 | 1 | 8 |
2 | 15 | |
3 | 16 | |
4 | 10 | |
2010 | 1 | 9 |
2 | 18 | |
3 | 18 | |
4 | 11 |
Question 1
Plot the data in on graph paper
Question 2
Using a 4 quarter moving average plot the resulting trend line.
Question 3
Calculate the seasonal variation for each quarter and use these figures to work out the average seasonal variation for each quarter
Question 4
Calculate the forecast sales for each quarter of 2011.
Sales of fashion shoes
Sales of modern fashion shoes were carefully recorded over the 20 months of its life and are published below.
Month |
Sales (pairs) |
Month |
Sales (pairs) |
---|---|---|---|
1 | 20 | 11 | 280 |
2 | 80 | 12 | 250 |
3 | 140 | 13 | 200 |
4 | 200 | 14 | 180 |
5 | 230 | 15 | 160 |
6 | 250 | 16 | 150 |
7 | 280 | 17 | 140 |
8 | 310 | 18 | 130 |
9 | 300 | 19 | 90 |
10 | 300 | 20 | 60 |
Question 1
Plot the data in the form of a scatter diagram, and attempt to identify any trend.
Question 2
Prepare a 4 month moving average, and plot the resulting trend line.
Question 3
Comment on your findings.
Honeydew Ice Creams
Sales of ice cream are highly seasonal, so can be hard to predict. Data recording sales of ice cream tubs for the last four years of trading for Honeydew is given below.
Q1 | Q2 | Q3 | Q4 | |
---|---|---|---|---|
2007 | 2500 | 5000 | 2500 | 1000 |
2008 | 2500 | 6000 | 3000 | 1000 |
2009 | 3000 | 6500 | 3000 | 1500 |
2010 | 3500 | 7000 | 3500 | 1500 |
Using time series analysis of the above data, calculate:
- The seasonal variation by quarter
- The best estimate of sales, by quarter for the year 2011.
Carry out this calculation using both 3 and 4 quarter moving averages