It depends what you want to predict.If you just want a probability distribution of 1-month LIBOR one year from today, you don't need a complicated model. You could look at historical data, comparing 1-month LIBOR at time t with 1-month LIBOR and 12-months-forward 1-month LIBOR; both from a year earlier. If that wasn't accurate enough, you could bring in other explanatory variables.The trouble is if you want to predict combinations of interest rates, say 1-month and 3-month LIBOR one year from today; or the move in 1-month LIBOR 1 years from today versus 2 years from today; or the correlation between 1-month LIBOR moves and 3-month LIBOR moves. Then you need a model of interest rates.Generally you have a choice between models that are accurate about interest rate movements and models that give realistic yield curves. Depending on your application you might prefer one or the other.