Multivariate time series model- VAR (http://cran.r-project.org/web/packages/vars/vignettes/vars.pdf) is the one to captue the dynamics and correlations followed by Granger causality, Impulse Response Function and FEVD.
We recommend using cross-correlation and then use dynamic regression or cointegration models time-series, according to the nature of the series. for more information write to email [email protected]; [email protected]
... where B3XZ is the interaction between XZ and verify whether this interaction is significant by:
(2) T = (B1 - B2) / SQRT((C + D) / E)
(2.1) C = n1SE12
(2.2) D = n2SE22
(2.3) E = n1 + n2 - 2
If the test verifies as significant, use (1) above as the general model. If the test shows insignificant, then the model is reduce to a simple regression: