Comparability of Producer Price Indexes and Import Price Indexes
The Bureau of Labor Statistics (BLS) publishes both Producer Price Indexes (PPIs) and Import Price Indexes (MPIs) classified according to the North American Industry Classification System (NAICS). This allows for the possibility of comparing price trends using NAICS-based PPIs and MPIs. There are, however, important potential differences between PPIs and MPIs that data users should consider before comparing the two series.
The PPI-MPI Comparability Table, available for download below, assists data users in determining comparability between PPI industry net output indexes and MPI industry indexes by providing data on these potentially important differences. A full description of the data included in the table, explanations of potential differences between PPIs and MPIs, and comparison examples can be found in the Monthly Labor Review (MLR) article Comparing NAICS-based PPI Industry Net Output Data and International Price Program Import Data.
The PPI-MPI comparability table is structured as followed:
Column 1 provides the NAICS title of the industry or industry group.
Column 2 indicates NAICS industry codes for the data included in the table.
Column 3 provides relative-importance values of 6-digit industries to the 4- or 5-digit MPIs.
Column 4 shows relative-importance values of 6-digit industries to the 4- or 5-digit PPIs.
Column 5 indicates the net output ratios the PPI program applies to each industry weight when constructing 4- or 5-digit PPI industry group indexes.
Column 6 provides the percentage of primary production for each 4- and 5-digit NAICS-based PPI.
When all else are equal, comparability between a PPI and MPI industry group index increases with
Increased similarity in relative importance values between PPIs and MPIs.
More uniform PPI net output ratios for industries included in the industry.
Higher percent primary for the industry group.
When using this table, data users should keep in mind these important caveats:
Determining the level of comparability necessary to make valid comparisons is subjective and the responsibility of the data user.
Though indexes may appear similar on the basis of relative importance values, net output ratios, and percent primary, differences in the sampled product mixes may still make comparisons problematic.
When comparing PPIs and MPIs, no inferences can be made with respect to differences or similarities in absolute price levels of domestically produced versus foreign produced products.