LEAP does not directly support statistical models like ARIMA or ARDL, so you'll need to perform those regressions in external tools such as R, Python, or Excel to forecast future energy demand based on variables like GDP, population, and energy intensity. Once you have your forecast results, you can input them into LEAP using functions like Interp(...) or by setting up scenario expressions. You can also define GDP, population, and energy intensity as Key Assumptions in LEAP and use your regression coefficients in LEAP expressions to calculate demand. While LEAP can't estimate the models itself, it allows you to integrate their outputs into your scenario analysis framework.