(a) What are the main components of a time series? Briefly describe them. (b) The plot of a monthly time series is given in the figure below: What are the components of this time series? Please describe them. (c) Which is the appropriate (additive or multiplicative) decomposition model for the time series in part (b)? (d) Describe the decomposition method identified in part (c) by showing all the major steps. (a) What are the main components of a time series? Briefly describe them. (b) The plot of a monthly time series is given in the figure below: What are the components of this time series? Please describe them. (c) Which is the appropriate (additive or multiplicative) decomposition model for the time series in part (b)? (d) Describe the decomposition method identified in part (c) by showing all the major steps