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Producer Price Indexes
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PPI Introduces Hedonic Quality Adjustment for Internet Access Indexes
Effective with the release of Producer Price Index (PPI) data for December 2016, on January 13, 2017, the Bureau of Labor Statistics began using hedonic quality adjustment for broadband items within PPI data for Internet access services:
- PCU5173115173116 — Wired telecommunications carriers: Internet access services
- WPU3741 — Telecommunication, cable, and internet user services: Internet access services
Broadband Internet access services include digital subscriber lines (DSL), cable, and fiber optic services. These services are subject to rapid technological change because download and upload speeds typically increase over time. This means specific items within the broadband internet access sample of the PPI periodically are replaced with items with faster download and upload speeds.
To account for these changes, we must determine the value of quality adjustment (VQA)—the value of the increased broadband download or upload speed. Ideally, PPI survey participants would provide this information, but often this does not occur. As a result, we use a hedonic model to estimate the value of the increased speed. The regression formula used in the hedonic model is based on Equation 1, and the results for 2016 are shown in Table 1.
Equation 1
Log Pit = Α0 + Β2 (Log X2i) + Β3 (Log X3i) … (Βk Log Xki) + Υi
- Where:
- Log Pit is the Log price of the i th model in period t
- Α0 is the intercept
- Log Xi are the logged variables representing observed product characteristics
- Β2 … Βk are the regression/slope coefficients
- Υi is the residual or error term
Table 1. PPI Hedonic Model Regression results for broadband internet access for 2016 a,b,c
| Coefficient | Standard Error | t-statistic | P-value | Variance Inflation Factor | |
|---|---|---|---|---|---|
(Intercept) | 2.8844 | 0.3072 | 9.390 | 0.000 | - |
Log Download Mbps | 0.3075 | 0.0977 | 3.147 | 0.005 | 23.6840 |
Residential | 0.0320 | 0.3352 | 0.095 | 0.925 | 86.0865 |
Company A | 0.5906 | 0.1025 | 5.762 | 0.000 | 4.9199 |
Company B | 0.7529 | 0.1539 | 4.892 | 0.000 | 18.3561 |
Company C | 0.7068 | 0.1551 | 4.557 | 0.000 | 5.1195 |
Log Download: Residential | 0.1411 | 0.1096 | 1.287 | 0.213 | 50.5616 |
Log Download: Company B | -0.8863 | 0.1684 | -5.263 | 0.000 | 16.9078 |
(a) Adjusted R-Squared = 0.9400; F = 59.17; Root Mean Squared Error = 0.0933 | |||||
The main variables of interest in this model are Log Download Mbps and Log Download: Residential. These two variables permit changes in download speed to be valued for both residential and business broadband. In this case, Log Download: Residential is not significant, which implies that there is no difference in the pricing behavior between residential and business broadband Internet access services.
PPI plans to re-estimate the hedonic broadband Internet access model annually.
Learn more about the use of hedonic models in the PPI »
For further information on PPI data for Internet access services, contact Jason Carnival at carnival.jason@bls.gov or (202) 691-7734.
Last Modified Date: March 6, 2019