Given the SACF and SPACF for each of the following stationary time series, discuss with reasons what ARMA(p,q) model you would consider the most appropriate. For full marks you must choose one model, justify your choice clearly and determine the sign (positiveegative) of any parameters.

2. [3 marks each] Given the SACF and SPACF for each of the following stationary time series, discuss with reasons what ARMA(p, q) model you would consider the most appropriate. For full marks you must choose one model, justify your choice clearly and determine the sign (positiveegative) of any parameters. (a) Series A Series seriesA Series seriesA ACF 0.0 0.4 Partial ACF 0.4 J.O 10 15 20 10 15 20 Lag Lag (b) Series B Series seriesB Series seriesB ACE -0.5 0.0 0.5 1.0 Partial ACF -0.5 -0.3 -0.1 0.1 10 15 20 10 15 20 Lag Lag\f