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Source: U.S. Department of Energy, Energy Information Administration (government).
Petroleum supply data are collected by the Petroleum Division in the Office of Oil and Gas of the Energy Information Administration (EIA), U.S. Department of Energy (DOE). The Bureau of Transportation Statistics (BTS) produced the pipeline component of the Transportation Services Index (TSI) using two data sources, from EIA, the Monthly Product Pipeline Report and the Monthly Crude Oil Report, both of which are published in DOEs Petroleum Supply Monthly.
Monthly petroleum supply data include the measurement of supply and the disposition of crude oil and petroleum products at both national and regional levels. The data series describe production, imports and exports, movements, and inventories of petroleum products in thousands of barrels. The Monthly Petroleum Supply Reporting System (MPSRS) was implemented in January 1983.
A sample is a subsection of universe-identifying members of a target population. There are five samples, one for each weekly petroleum supply survey, in the Weekly Petroleum Supply Reporting Systems (WPSRS). The weekly surveys are administered to samples of the monthly populations to reduce respondent burden and to expedite the turnaround of data from survey respondents to the public. As with any sample, the value obtained differs from that obtained if the full universe is surveyed.
Sampling error is the difference between a sample estimate and a population value. For these surveys, the EIA minimizes the sampling error by using a minimum 90% multiattribute-cutoff sample of the corresponding monthly surveys frame. At the end of each month, updates are made to the samples and survey frames if 90% coverage was not obtained.
For the weekly surveys, better coverage will likely reduce sampling error. Of the 21 products and supply type combinations, 19 had coverage of 90% or above in 2001. For 11 of the 21 combinations, 2001 coverage increased from 2000. Tabulations were done before rounding of the coverage values. Jet fuel imports display a large percentage increase from 2000 to 2001, from 64 to 91% because of the resolution of noncompliance issues.
Unlike sampling errors, all survey data, even those from a census survey, are at risk of incurring nonsampling errors. There are two categories of nonsampling errors, random and systematic. With random error, on average, and over time, values will be overestimated by the same amount they are underestimated. Therefore, over time, random errors do not bias the data, but they will likely give an inaccurate portrayal at any point in time. On the other hand, systematic error is a source of bias in the data because these patterns of errors are made repeatedly.
The list of all companies identified as members of the target population is called a frame. If members of the target population are not included in the frame, there is an undercount of the aggregate data. To diminish the chance of undercounting, the MPSRS frames are continually updated. New companies are identified through continual review of petroleum industry periodicals, newspaper articles, and correspondence from respondents.
EIAs authority to collect data comes from several laws, including the 1974 Federal Energy Administration (FEA) Act (P.L. 93-275, 15 USC 761), the 1976 Energy Conservation and Production Act (P.L. 94-385, 15 USC 790) and the1977 Department of Energy (DOE) Organization Act (P.L. 95-91, 42 USC 7135), which established EIA as the single federal government authority for energy information and gave EIA independence from the rest of DOE with respect to data collection, and from the whole government with respect to the content of EIA reports.
Data Quality Questions
- Is this data source a frame or a sample?
There are five samples, one for each weekly petroleum supply survey, in the Weekly Petroleum Supply Reporting Systems (WPSRS).
- Does the sample cover the entire frame? Or is some group missing or underrepresented in the sample?
The data sources are Form EIA-812, Monthly Product Pipeline Report and Form EIA-813, Monthly Crude Oil Report. These surveys go to all pipeline operators in the United States. The only movement data that EIA collect are movements that cross Petroleum Administration for Defense District (PADD) boundaries. Movements within PADDs are not recorded. The good coverage for weekly surveys across petroleum supply type and product combinations has contributed to the accuracy of weekly estimates. In 2001, for 19 of the 21 categories, coverage was 90% or above. All of the 2001 response rates for the weekly and monthly surveys decrease from the 2000 rates. Company mergers and budget constraints may have contributed to the decrease in response rates.
- Are the data available monthly?
Yes. Data come out each month in the Petroleum Supply Monthly (PSM). Revisions are published in the Petroleum Supply Annual (PSA).
- How soon are the data available after the month is over?
They are published on the website or in the PSM publication book within 2 months after the closing of a reference month. The reference period of the monthly surveys starts on the first day of the month at 12:01am and ends on the last day of the month at midnight.
- Are the data easy to access and use?
Yes, the data are easy to access and use, and can be found at http://www.eia.doe.gov/oil_gas/petroleum/data_publications/petroleum_supply_monthly/psm_historical.html.
The survey forms are available on the website at http://www.eia.doe.gov/oil_gas/petroleum/survey_forms/pet_survey_forms.html.
- Are the microdata available for use?
No, not on the Web site.
- Are there duplicate records?
- Are there outliers in the data?
Yes, but EIA runs automated edit programs against all of the data and follows up with reporting companies after finding significant outliers or discrepancies.
- Are data missing for individual records? If so, how are they identified?
Pipeline operators are required by law to report, but there have been some cases of no response. EIA imputes data values for nonresponders and then follows up with companies to get the missing reports. Final data published in the Petroleum Supply Annual typically includes data from all or nearly all pipeline operators. For monthly data, EIA response rates tend to be very high (generally 95% or better). EIA publishes an article on data quality each year in the Petroleum Supply Monthly.
- How accurate are the key data fields?
Two major factors that contribute to the Petroleum Supply Monthly (PSM) values being more accurate than the monthly-from-weekly (MFW) estimates are the greater length of time between the close of the reference period and the publication date of the PSM. Most MFW values (weekly data converted to a monthly value) are based on companys operational records, whereas PSM values are generally extracted from companys accounting systems, the latter being more accurate.
Accuracy of petroleum supply data can be found at http://www.eia.doe.gov/pub/oil_gas/petroleum/feature_articles/2002/accuracy_of_petroleum_supply_data/art0209.pdf.
- Are variances available for this data source? If so, what method was used to calculate variances?
- Are the data comparable over time within the data source? If not, can data be made to be comparable (e.g., combining two data series)?
Data are generally consistent over time. EIA sometimes adds or deletes product detail. For example, while pipeline movement of finished gasoline is always provided detailed breakdowns within finished gasoline may change over time.
Other Questions and Important Information
- Is sufficient documentation available for the data source?
All documentation and information are posted on
- Data dictionary:
Please see the Petroleum Supply Monthly Definitions of Petroleum Products and Other Terms at
- Detailed description of the methodology:
Please see the Detailed Statistics Explanatory Notes at
- Estimation methods:
Please see the Detailed Statistics Explanatory Notes at
- Are other sources available for the same data?
There are no other sources available for the same data at this time.
- Who is the contact for the data source?
U.S. Department of Energy (USDOE), Energy Information Administration (EIA), Monthly Product Pipeline Report, 202/586-1795, http://www.eia.doe.gov.
USDOE, EIA, Monthly Crude Oil Report, 202/586-3536, http://www.eia.doe.gov