The TYDL procedure uses a modified-Wald test for restrictions on the parameters of the VAR( k) model. This test has an asymptotic chi-squared distribution with k degrees of freedom in the limit
when VAR[k þ d max ] is estimated. Here d max is the maximal order of integration for the series in the system. Following Dolado and Lütkepohl , we use d max ¼ 1 as it performs better than other
orders ofd max . We estimate the VAR equations: