To decide the value of d for an ARIMA(p, d, q) model for a time series y, plots were created using the R program: 8 par(mfrow=c(3,2))  9 plot(y,type="l")  10 acf(y)  11 plot(diff(y),type="l") 12...

To decide the value of d for an ARIMA(p, d, q) model for a time series y, plots were created using the R program:

8 par(mfrow=c(3,2))

 9 plot(y,type="l")

 10 acf(y)

 11 plot(diff(y),type="l")

12 acf(diff(y))

13 plot(diff(y,d=2),type="l")

 14 acf(diff(y,d=2))

 The output was the following figure: