part B

B. Collections of Information Employing Statistical Methods
B1. Description of the Survey Plan
Frames maintenance activities are conducted on a monthly and annual basis. Response to all
PSRS surveys is mandatory.
Monthly Frames Maintenance
The monthly frames maintenance procedures focus on examining several frequently published
industry periodicals that report changes in status (births, deaths, mergers and changes in ownership)
of petroleum facilities producing, transporting, importing, and/or storing crude oil and petroleum
products. These sources are augmented by articles in newspapers, letters from respondents
indicating changes in status, and information received from survey systems operated by other
offices. At the same time, the sample frames for the weekly surveys are also updated. A sample
control meeting is conducted each month. This meeting focuses on changes in the current monthly
data as it relates to the weekly surveys, changes in the weekly surveys that impact the monthly
surveys, and changes in respondent reporting patterns. These meetings are conducted to assure a 90percent coverage of the total for each item collected and each geographic region for each of the
weekly surveys.
Annual Frames Maintenance
The annual frames maintenance is conducted to re-evaluate the consistency of frames between
the Forms EIA-810 and EIA-820.
2. Sampling Methodology and Estimation Procedures
The frame of respondents is considered as the universe for all PSRS surveys with the exception
of the following surveys:
EIA-800, “Weekly Refinery and Fractionator Report”
EIA-801, “Weekly Bulk Terminal Report”
EIA-802, “Weekly Product Pipeline Report”
EIA-803, “Weekly Crude Oil Stock Report”
EIA-804, “Weekly Imports Report”
EIA-805, “Weekly Terminal Blenders Report”
EIA-809, “Weekly Oxygenate Report.”
a.

Sampling Frame

The EIA weekly reporting system, as part of the PSRS, was designed to collect data similar to those
collected monthly. The sample of companies that report weekly in the WPSRS are selected from the
universe of companies that report on the corresponding monthly forms.
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The sampling frame for Form EIA-800 “Weekly Refinery Report” includes refineries reporting on
Form EIA-810 “Monthly Refinery Report” as well as gas processing plants and fractionators
reporting on Form EIA-816 “Monthly Natural Gas Liquids Report.” Monthly reports on Form EIA810 are required from operators of every operating and idle refinery located in the 50 States, District
of Columbia, Virgin Islands, Puerto Rico, and other U.S. territories. Monthly reports on Form EIA816 are required from operators of every operating and idle gas processing plant fractionator, and
butane isomerization plant located in the 50 States and the District of Columbia.
The EIA-801 sampling frame consists of all companies reporting ending stocks on the EIA-815,
“Monthly Terminal and Blender Report.” This includes every bulk terminal operating company
located in the 50 States, the District of Columbia, Puerto Rico, and the Virgin Islands. A bulk
terminal is primarily used for storage and/or marketing of petroleum products and has a total bulk
storage capacity of 50,000 barrels or more, and/or receives petroleum products by tanker, barge, or
pipeline. Bulk terminal facilities associated with a product pipeline are included.
The EIA-802 sampling frame consists of all companies reporting on the EIA-812, “Monthly Product
Pipeline Report.” This includes all petroleum product pipeline companies that transport refined
petroleum products (including interstate, intrastate, and intracompany pipeline movements) in the 50
States and the District of Columbia.
The EIA-803 sampling frame consists of all companies reporting on the EIA-813, “Monthly Crude
Oil Report.” This includes all companies that carry or store 1,000 barrels or more of crude oil.
Included are gathering and trunk pipeline companies (including interstate, intrastate, and
intracompany pipelines), crude oil producers, terminal operators, storers of crude oil (except
refineries), and companies transporting Alaskan crude oil by water in the 50 States and the District
of Columbia.
The EIA-804 sampling frame consists of all companies reporting on the EIA-814, “Monthly Imports
Report.” This includes all companies, including subsidiary or affiliated companies, that import
crude oil or petroleum products (1) into the 50 States and the District of Columbia, (2) into Puerto
Rico, the Virgin Islands, Guam and other U.S. possessions (Midway Islands, Wake Island, American
Samoa, and Northern Mariana Islands), and (3) from Puerto Rico, the Virgin Islands and other U.S.
possessions into the 50 States and the District of Columbia. Imports into Foreign Trade Zones
located in the 50 States and the District of Columbia are considered imports into the 50 States and
the District of Columbia and must be reported.
The EIA-805 sampling frame consists of all companies reporting inputs and production on the EIA815, “Monthly Terminal Blender Report.” This includes all storage terminals which produce
finished motor gasoline through the blending of various motor gasoline blending components,
natural gas liquids, and oxygenates in the 50 States, the District of Columbia, Puerto Rico, the
Virgin Islands, Guam and other U.S. possessions.
The EIA-809 sampling frame consists of all companies reporting on the EIA-819, “Monthly
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Oxygenate Report.” This includes all operators of facilities that produce fuel ethanol located in the
50 States and the District of Columbia.
b. Sample Design
The sampling procedure used for all the sampled surveys is the cut-off method. In the cut-off
method, companies are ranked from largest to smallest on the basis of quantities reported during
some previous period. Companies are chosen for the sample beginning with the largest and
adding companies until the total sample covers approximately 90 percent of the total volumes for
each item and each geographic region for which data may be published.
To ensure 90-percent coverage of the total for each item collected and each geographic region for
each weekly survey, a sample control meeting is conducted each month. This meeting focuses on
changes in the current monthly frame due to sales, acquisitions, mergers, new reporters, and
reactivations. Companies are added or removed from the weekly reporting samples based on the
changes.
c. Imputation and Estimation Procedures
EIA-800 through EIA-809
After company reports have been checked and entered into the weekly database, values are imputed
for companies that have not responded, reported incomplete data, or reported data that failed editing
and could not be confirmed. The imputed values are calculated using exponentially smoothed means
of recent weekly reported values for this specific company.
The equation for the exponential smoothing is:
Yt = α * yt + (1 - α) * Yt-1
where

Yt
yt
Yt-1
α

is the prediction for week t+1 (using data through week t),
is week t's reported value,
is the prediction for week t (using data through week t-1),
is a number between 0 and 1, chosen by survey/product/type

In the equation for exponential smoothing, the size of α controls the importance of last week’s value
relative to the aggregate of all weeks before that as represented by the prediction for last week. For
example, if α = 0.8, then last week’s value is much more important in predicting this week’s value
than all the previous week’s values are since the weight of last week is 0.8 and the weight of the
previous weeks collectively is 0.2. In general, the α values for the expected means of the non-zero
responses are low for imports (last week is much less important than history) and much higher for
production, inputs and stocks.
The imputed values are treated like reported values in the estimation procedure, which calculates
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ratio estimates of the weekly totals. First, the current week’s data for a given product reported
by companies in a geographic region are summed (weekly sum, Ws.) Next, the most recent
month’s data for the product reported by those same companies are summed (monthly sum, Ms.).
Finally, the most recent month’s data for the product as reported by all companies, including
adjustments
made in the monthly process, is summed (Mt). The current week’s ratio estimate for that product for
all companies, Wt, is given by:
Wt= (Mt / Ms) * Ws
The ratio (Mt / Ms) may be adjusted to account for very unusual events or industry changes not yet
reflected in the lagged monthly data. For example, the hurricanes in September 2005 rendered the
September data unrepresentative for purposes of applying the ratio to the WPSR in December 2005.
This procedure is used directly to estimate total weekly inputs to refineries and production. To
estimate stocks of finished products, the preceding procedure is followed separately for refineries,
bulk terminals, and pipelines. Total estimates are performed by summing over establishment types.
Weekly imports data are highly variable on a company-by-company basis or a week-to-week basis.
Therefore, an exponentially smoothed ratio has been developed for weekly imports. The estimate of
total weekly imports is the product of the smoothed ratio and the sum of the weekly reported values
and imputed values.
For imports, the ratio is smoothed as follows:
Rt = α * rt + (1 - α) * Rt-1
where

Rt
rt

is the smoothed ratio for week t+1 (using ratios through week t),
is week t's ratio of the most recent monthly total for all respondents to the
monthly total of respondents from the weekly sample,
is the smoothed ratio for week t (using ratios through week t-1),
Rt-1
α
is a number between 0 and 1, chosen by product but not by
PADD/Respondent ID.

When Ms = 0, then rt is not defined for the week and the smoothed ratio is not updated, that is, the
previous smoothed ratio is used as the multiplier.
Forms EIA-810 through 813, 815, 816, and 819
In any survey, non-response can be a major concern because the effects can cause serious bias in
survey results. Non-response occurs whenever requested information is not obtained from all units
in a survey. Response rates for these surveys are generally 99 to 100 percent. Whenever survey
responses are not received in time to be included in published statistics, the data are imputed.
Although imputing for missing data may not eliminate the total error associated with non-response,
it can serve to reduce the error. The data reported in the previous month are used as imputed values
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for missing data. Data are not imputed for the EIA-814 and 817 because these data series, by
respondent, are highly variable.
d. Macro Editing
EIA-800 through 809
After the flagged respondent data have been resolved, preliminary tables are produced and used to
identify anomalies. These tables show U.S. and PADD estimates for the current week and the prior
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weeks and also show year-ago data for the same week along with 4 week average. Anomalies result
in further review of respondent data which in turn may result in additional flagged data and
imputation.
EIA-810 through 819
After the flagged respondent data have been resolved, preliminary tables are produced and used to
identify anomalies. These tables show U.S. and PADD estimates for the current month and the prior
4 years. Anomalies result in further review of respondent data which in turn may result in additional
flagged data and imputation. In addition, other adjustments are made to aggregate data from time to
time. For example, unusual industry conditions, including fuel transitions, business practice shifts,
or hurricane dislocations, may generate reporting anomalies and require adjustments. Measurement
error and frame deficiencies may occasionally result in inconsistencies when individual respondent
data are aggregated to publication levels and require adjustment. Monthly supply data are reviewed
throughout the year and some estimates may be replaced with newly available or resubmitted
respondent data in the Petroleum Supply Annual (PSA).
e. Data Accuracy
The reliability of data is subject to two types of possible errors, non-sampling errors and sampling
errors. Sampling errors occur because observations are made only on a sample, not on the entire
population. Non-sampling errors can be attributed to many sources in the collection and processing
of data such as, response coverage; a difference in interpretations of definitions or questions;
mistakes in recording or coding the data from respondents; and other errors of collection and
estimation. The accuracy of survey results is determined by the joint effects of sampling and nonsampling errors.
For the monthly surveys EIA-810, 812, 813, 815, 816, 817, 819 and the annual survey EIA-820,
there is no sampling error because the surveys are based upon a complete census of the frame.
However, response error is the major factor affecting the accuracy of data. Response error, or
reporting error, is the difference between the true value and the value reported on a survey form.
To aid in detecting and minimizing reporting errors, automated editing procedures are used to check
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current data. These checks include verifying the current data for consistency with past data, for
internal consistency (e.g. totals equal sum of parts), examining orders of magnitude, and cell
position. Data elements that fail edit criteria are flagged.
Monthly and weekly data are compared on a regular basis to rectify discrepancies in data. In
addition, a comparison of PSRS data with sources outside of the Petroleum Division is performed
each year. The results of this effort have been published in the feature article, “Accuracy of
Petroleum Supply Data, 2007” located on the Internet.
B3. Methods to Maximize Response Rate
To maximize response rates, forms are designed to be easily completed, and instructions are written
to be clear, concise, and easily understood. Forms and instructions are made available on our
website. Survey nonrespondents are contacted by telephone to discuss the requirement to file and
any problems or questions that are delaying filing. Follow-up letters regarding the failure to file may
be emailed to respondents. Specific schedules are followed for telephone calls and letters to
nonrespondents for the various surveys. Every effort is made to assist respondents in completing the
survey and submitting them in a timely manner. The response rate for weekly surveys averages
above 97 percent. The response rate for monthly surveys is 99 to 100 percent.
4. Test Procedures
The petroleum surveys are established continuing surveys. Modifications to all of the existing forms
were made by the EIA staff in conjunction with discussions with industry representatives and
consultations through the Federal Register notice discussed earlier. These actions served as a test of
the availability of data and the clarity of instructions of the survey forms, as well as the proposed
modifications.
5. Questions
Questions regarding the Petroleum Supply Reporting System may be directed to Sylvia Norris of the
Department of Energy, Energy Information Administration, at (202) 586-6106. Questions regarding
the EIA Forms Clearance process should be directed to Grace Sutherland at (202) 586-6264.

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