How do the source data and estimating methods compare for estimating the IPI and GDP for goods?

For current periods, GDP goods estimates primarily reflect monthly Census source data (GDP methodologies and source data), while the IPI estimates reflect a mix of energy use, tons of materials shipped, and employment indicators. For historical periods, both the IPI and GDP goods reflect more of the same Census source data (e.g., the Annual Survey of Manufactures). As a result, differences in the movements of the two series for current periods tend to diminish when examining historical periods.