Chapter 4, Problem 6P

The monthly sales for Yazici Batteries, Inc., were as follows:

MONTH	SALES
January	20
February	21
March	15
April	14
May	13
June	16
July	17
August	18
September	20
October	20
November	21
December	23

1. a. Plot the monthly sales data.
2. b. Forecast January sales using each of the following:
   1. i. Naive method.
   2. ii. A 3-month moving average.
   3. iii. A 6-month weighted average using .1, .1, .1, .2, .2, and .3, with the heaviest weights applied to the most recent months.
   4. iv. Exponential smoothing using an α =. 3 and a September forecast of 18.
   5. v. A trend projection.
3. c. With the data given, which method would allow you to forecast next March’s sales?