Questions on Time Series Tutorial

timeseries

#1

I have some questions regarding this article

The author found the parameters p, d, q through trial and error minimizing AIC and/or BIC. What are the commands for calculating AIC or BIC in R? What is the philosophy behind choosing p,d,q? What does it mean that d=2 or 3 or 4?


#2

Hi @luvsuneja,

You can simply use Auto Arima to determine the best set of p,q, d. (If you face any issues in determining the values using auto arima, let us know)

Regarding the d value, when d = 1 , the differencing operation on the series was performed once. For d = 2 , the differencing is performed twice. Maximum number of times, d = 1 is sufficient to make the series stationary . Here is a small example to explain differencing clearly (each value is subtracted with the next value) -

 value     D = 1

  100       NaN
  120       20
  130       10
  160       30
  170       10
  180       10