I have time series data which is international monthly tourist arrival to Malaysia (N=264).
My objective is to forecast tourist arrival for 6 months ahead. After analyzing my data pattern, I found that using Box-Jenkins method gives me the best forecasting model.
The question is that, at such preliminary stage, when using Box-Jenkins methodology time series data must follow certain criteria: mean is zero, variance is constant and the data is stationary.
I used graphical methods to check if my time series data is stationary, has zero mean and constant variance.
However, how to check whether my time series data is independent and identically distributed (iid)? What method should i used?