Intervention time series modeling with parametric and nonparametric approach: comparative study on Corporation tax in Togo

Time series are often subject to structural changes caused by external events such as strikes, new fiscal measures, or policy changes. In the current paper, we conduct a comparative study of a parametric and nonparametric approach to intervention time series modeling to model the impact, on corporate tax, of the important tax reform in December 2012 in Togo (the establishment of a Togolese Revenue Office).The comparison of the two models has led us to conclude that the non-parametric approach is superior in terms of predictive quality as well as the measurement of the effect of the reform.