## 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:

1. The seasonal variation by quarter
2. The best estimate of sales, by quarter for the year 2011.

Carry out this calculation using both 3 and 4 quarter moving averages