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#In question 1,Haider decided to choose the log and log difference, before he see if the data are stationary or non-stationary.he has to explaine that we need to use them to transform data from non-stationary data to stationary.
#In question 3 he does not use log, log-change, seasonal log change. I think he should to try different model until he find best model with on resduals corrolation.however, I learned alot from his answers. He explaine the reasons for using test. Also, for forcaste part, his answer was very good.