Chapter 7 General ADAM ETS model
Now that we have discussed two special cases of ADAM ETS models (namely pure additive from Chapter 5.1 and pure multiplicative from Chapter 6.1 ADAM ETS), we can move to the discussion of the general model and special cases of it, including some of mixed models. We will consider two important groups of mixed ADAM ETS models: with non-multiplicative and with multiplicative trends. They have very different properties that are worth mentioning. Finally, we will discuss the question of normalisation of seasonal indices. This topic has been studied in the literature back in 80s, when we still did not have a proper ETS model, but has not been thoroughly discussed since then. In Section 7.5, we take a more critical view towards the topic.