I am trying to fit a time series with function
auto.arima in the "forecast" package in R that is choosing the best model automatically. Since I am using it for my thesis, I have to show the trace of stepwise selection algorithm manually (without adding line "trace" in
auto.arima code) with my web apps here https://nugraha92.shinyapps.io/Analisis/
But, when I manually checked it, I found that
auto.arima did not choose minimum AIC values.
Then, I input the
trace=TRUE line and the result shows that the AIC/BIC value is not the same between the "trace ARIMA list" and "choosen ARIMA model". For example, in the image it is shown that the best model is ARIMA(3,1,3), BIC score at the list is -252.4451 while at the equation below is -250.89.
Why and which one is the correct one? Did I make some mistakes?