Figure 8.6 shows some data from an MA(1) model and an MA(2) model. Changing the parameters θ1,…,θq results in different time series patterns. As with autoregressive models, the variance of the error term et will only change the scale of the series, not the patterns.
It is possible to write any stationary AR(p) model as an MA(∞) model. For example, using repeated substitution, we can demonstrate this for an AR(1) model :