Impact of the coronavirus (COVID-19) pandemic on the Producer Price Index data for December 2020

The Producer Price Index (PPI) is a measure of the average change over time in the prices domestic producers receive for the sale of their products. PPI estimates for December 2020 were published on January 15, 2021. The pricing date was Tuesday, December 15, 2020, which means that most producers, but not all, provided prices they received on that date. The summary statistics in tables 1, 2, 3 and 4 indicate the impact of the COVID-19 pandemic on the PPI data collection, index estimation, and the BLS ability to publish indexes was minor for the release of preliminary December data. No changes in estimation procedures were necessary.

This page provides information on the effects of the COVID-19 pandemic for the December 2020 Producer Price Indexes news release.

Collection mode

The PPI collects nearly all of its repricing data by web collection. There were no changes to collection mode in response to the pandemic.

Response rates

Table 1 provides the December 2020 response rate by industry sector, along with comparison periods of November 2020, December 2019, and a 12-month average for March 2019 to February 2020. The December 2020 response rate for items requested shows a similar level of response for the majority of industry sectors. While the response rate for the entertainment, accommodation, and food services sector remains down when compared to historical comparison periods, the December 2020 response rate has stabilized somewhat relative to the November 2020 response rate.  While the preliminary December response rates for several other sectors slipped somewhat from November, the holiday season typically experiences a slight depression in initial response rates, and the response rates for these sectors are consistent with their respective rates in December 2019 and the March 2019 to February 2020 averages.

It is important to note that typically the PPI survey’s monthly price collection response rate averages 76 percent by the end of its 4-month index revision period. All PPI indexes are recalculated 4 months after publication of preliminary data. Thus, December indexes may be revised when BLS publishes the PPI for April on May 13, 2021. All summary statistics in the tables below reflect comparisons to PPI preliminary data.

Imputation

When a respondent does not provide a price for an item, BLS employs an imputation method of replacing that missing price with a statistically estimated value. Missing prices are imputed by the prices of similar items that have been collected. Essentially, the price movements of items that are not collected are estimated to be the same as those in their general index category. Table 2 indicates that the December 2020 item imputation rate of 41 percent reflects an increase from the preceding month and the average calculated over March 2019 to February 2020.

Cell, series, index, or observation suppression

BLS calculates over 10,000 PPIs for individual products and groups of products for publication during the release of preliminary data. The first row of Table 3 shows the December 2020 publication rate of 88 percent is very similar to the comparison periods. BLS suppresses indexes when they fail to meet publication criteria. Because of additional collection efforts along with late-arriving data, these suppressed indexes often will meet publication criteria at the end of the 4-month index revision period, at which time they are published. (Upon request, BLS will provide a list of indexes that did not meet publication criteria for the release of preliminary PPI data. Please email requests to ppi-info@bls.gov.)

Further illustrating the nominal impact of the COVID-19 pandemic, the second row of Table 3 shows the percent of industry indexes that BLS was unable to calculate because BLS did not receive any prices for that index. This proportion of not calculated indexes for December 2020 is similar to the normal result.

Table 4 takes a closer look at the not calculated PPI indexes by industry and reflects that across all industry sectors there is no discernable difference between December’s result when compared with earlier periods.

Last Modified Date: January 15, 2021