Code for ARIMA with intervention. Original data is the monthly Spot Crude Oil Price: West Texas Intermediate (WTI) from January 1991 to October 2000, with the intervention being Asian Economic Crisis occuring at roughly January of 1997.
note: this is added for archival purposes. Original version is runnable, but I give no guarantees that code is runnable considering code may be accidentally or purposely edited without reverting to original state after first use