Additive Vs Multiplicative (MA)

Question 1

How to calculate seasonal variance ?

Answer 1

= actual - the MA

Question 2

Create table for seasonal variation (additive)

Answer 2

Put the seasonal variation dat in a table to work out seasonal variance avg

Question 3

How to forecast using additive ?

Answer 3

Last MA or last centred MA+ (number of periods that have elapsed since the last moving avg x general trend) +/- seasonal variance

Question 4

How to work out seasonal indices ?(multiplicative)

Answer 4

= actual / MA

Change it into a percentage

Question 5

How to forecast using the multiplicative model ?

Answer 5

(Last MA + (number of periods since last MA x general trend) ) x seasonal index