# Chapter 3: Vector Autoregressive Methods Previously, we have introduced the classical approaches in forecasting single/univariate time series like the Autoregressive-Moving-Average (ARIMA) model and the simple linear regression model. We learned that stationarity is a condition that is necessary when using ARIMA while this need not be imposed when using the linear regression model. In this notebook, we extend the forecasting problem to a more generalized framework where we deal with **multivariate time series**--time series which has more than one time-dependent variable. More specifically, we introduce **vector autoregressive (VAR)** models and show how they can be used in forecasting mutivariate time series. The [notebook](03_VectorAutoregressiveMethods.ipynb) is outlined as follows: * Multivariate Time Series model * Motivation * Univariate VS Multivariate Time Series * Examples * Foundations * Vector Autoregressive (VAR) Models * VAR(1) model * VAR(*p*) model * Choosing the order *p* * Building a VAR model * Structural Analysis * Impulse Response Function * Forecast Error Variance Decomposition * Takeaways * References