Interpretation of log transformed first differences in SVAR models I am working with a structural VAR analysis, and want to understand my results. 
I had to log transform and first difference 3 out of 4 variables. Are the outputs from the model how much the response variable increases from time period to time period, if they both are log transformed and first differenced? E.g. if the change from month 1 to month 2 is 2% and month 2 to month 3 is 1%, do I multiply the two to get the total effect for month 2 and 3? Or is the effect of month 2 a decrease relative to the first month? How about if I am looking at the variable that is only log transformed, and not first differenced. How do I interpret the percentage change?   
 A: Although I am not directly answering your question I want to recommend to look into SVAR Analysis with integrated series. This might solve your question more directly. Many authors argue that variables in SVARs shouldn't be first differenced. See for example:

Sims, C. A., Stock, J. H., & Watson, M. W. (1990). Inference in linear time series models with some unit roots. Econometrica: Journal of the Econometric Society, 113-144.
Ashley, R. A., & Verbrugge, R. J. (2009). To difference or not to difference: a Monte Carlo investigation of inference in vector autoregression models. International Journal of Data Analysis Techniques and Strategies, 1(3), 242-274.
Phillips, P. C., & Durlauf, S. N. (1986). Multiple time series regression with integrated processes. The Review of Economic Studies, 53(4), 473-495.
Lütkepohl, H. (2011). Vector autoregressive models. In International Encyclopedia of Statistical Science (pp. 1645-1647). Springer Berlin Heidelberg.
Christiano, L. J., Eichenbaum, M., & Evans, C. (1994). The effects of monetary policy shocks: some evidence from the flow of funds (No. w4699). National Bureau of Economic Research.
Doan, T. A. (1992). RATS: User's manual. Estima.ote

The Phillips, Durlauf and Ashley, Vergbugge papers even argue for SVARs in levels instead of VECMs if cointegration is present (under certain conditions).
Hope this helps!
