Anticipating revisions in the Transportation Services Index

Abstract

The Transportation Services Index (TSI) lags two months from its release date due to source data availability, and it is desirable to publish a preliminary TSI that is advanced two months ahead. We model and forecast TSI with a co-integrated Vector Autoregression, also considering two explanatory series that do not have publication delay. Thus we are able to produce forecasts and nowcasts of the index, and we demonstrate that – during normal economic conditions – out-of-sample performance is within the scope expected by the forecast confidence intervals. We also examine the performance of the models at the onset of the COVID-19 pandemic, and the large forecast errors at this regime change are beyond the bounds indicated by our model. The practical ramifications of this methodology is discussed.