Article
The m Process, denoted by MA(q) is believed to be a general finite order process which is an autoregressive form of a stationary sequence with covariance. It is stationary in the sense that the current conditional expectations is dependent on only a function of the lagged and current unobserved shocks. This function is the partial autocorrelation function.
MA(q) MA(q) is not an individual MA polynomial, which is different from AR processes. In fact, there are many possible MA(q) polynomials lag operator that could be stationary and have the same asymptotic properties.
It is therefore normal to impose invertibility restrictions on the MA polynomial to guarantee that the process is causal. This ensures that only previous events (not future ones) are able to predict future events.
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