2013 Supporting Statement Part B Oct 22 2012
2013 Supporting Statement Part B Oct 22 2012.docx
Electricity Data Program
OMB: 1905-0129
U.S.
Energy Information Administration Office
of Energy Statistics Office
of Electricity, Renewables, and Uranium Statistics
Supporting Statement for Survey Clearance
Electric Power Surveys
FORM EIA-923, POWER PLANT OPERATIONS REPORT, Schedule 2, Cost and Quality of Fuel Purchases – Plant Level;
FORM EIA-861, ANNUAL ELECTRIC POWER INDUSTRY REPORT;
FORM EIA-861S, ANNUAL ELECTRIC POWER INDUSTRY REPORT (SHORT FORM)
OMB No. 1905-0129
Part B: Collection of Information Employing Statistical Methods Appendix B-1: Part B of the Original Clearance Package Supporting Statement, September 2010 |
Revised October 22, 2012
Table of Contents
Part B: Collection of Information Employing Statistical Methods 3
B.1. Respondent Universe and Target Population 4
B.1.1. Form EIA-861, "Annual Electric Power Industry Report" 4
B.1.2. Form EIA-861S, "Annual Electric Power Industry Report (Short Form)" 5
B.1.3. Form EIA-826, "Monthly Electric Utility Sales and Revenue Report with State Distributions” 6
B.1.4. Form EIA-923, "Power Plant Operations Report” 6
B.2. Statistical Methodology for Sampling and Imputation 7
B.2.1. Forms EIA-861 and EIA-861S 7
B.2.2. Form EIA-826 8
B.2.3. Form EIA-923 9
B.3. Methods to Maximize Response Rates 9
B.4. Tests of Procedures 10
B.5. Forms Consultation 10
Appendix B-1: PART B OF THE ORIGINAL CLEARANCE PACKAGE SUPPORTING STATEMENT, SEPTEMBER 2010..12
Part B: Collection of Information Employing Statistical Methods
Background: Summary of Proposals
This section provides a summary of the proposed survey changes. The survey changes are discussed in detail in Part A of this supporting statement.
The proposed changes involve selected changes to two existing surveys, the Form EIA-861, "Annual Electric Power Industry Report" and Schedule 2 of the Form EIA-923, "Power Plant Operations Report." The proposal also includes the creation of one new survey, the Form EIA-861S, a short-form version of the current Form EIA-861.
The existing surveys are currently cleared by OMB through October 2013. Therefore these selected changes constitute a revision (supplement) to the existing clearance, not a replacement of or extension to the existing clearance. As with the existing electric power surveys, the proposed Form EIA-861S will expire in 2013 so that all the electric power surveys can be proposed for re-clearance as a group with common dates.
Form EIA-861, "Annual Electric Power Industry Report"
The Form EIA-861 is currently an annual survey of a universe consisting of all electric utilities in the United States and other related entities, such as power marketers. The frame consists of 3,300 entities. The data collected includes information related to electricity sales, customers, and demand response and energy efficiency activities.
Many of the survey respondents are very small and have difficulty providing accurate responses to the Form EIA-861 survey. The survey is burdensome for these small respondents and editing their responses consumes a disproportionate share of EIA’s resources.
EIA proposes to change the Form EIA-861 from a survey of all utilities and related entities to a survey of a sample of 2,200 larger respondents. The remaining 1,100 respondents – which in aggregate account for only about 1 percent of total U.S. electricity sales and rarely perform anything outside of basic electricity sales and distribution activities – would report on a new short form, discussed immediately below.
Form EIA-861S, "Annual Electric Power Industry Report (Short Form)”
The sample of this new annual survey would consist of the 1,100 respondents removed from the Form EIA-861 frame. The survey would collect very limited data from these respondents, primarily total sales, retail revenues, and customer counts. A statistical imputation methodology would be used to allocate sales, revenues, and customer counts to industry sectors (i.e., residential, commercial, industrial, and transportation).
Once every 5 years the Form EIA-861S respondents would be required to fill out the Form EIA-861 in lieu of the Form EIA-861S. This information will be used to verify and update the sample and the imputation methodology.
Summary of Proposal Related to Form EIA-923, "Power Plant Operations Report"
The Form EIA-923 is a mandatory report that collects a wide variety of data on the operations of power plants. Depending on the size (megawatt capacity) of a plant it reports either monthly or annually.
This proposal affects only Schedule 2, “Cost and Quality of Fuel Purchases – Plant-Level,” which collects information on the cost, quality, and volume of combustible fuel receipts. Currently, plants must report these data only if the plant meets a minimum capacity threshold of 50 megawatts (MW) of nameplate capacity or greater.
As in the case of the Form EIA-861, EIA has found that smaller respondents have difficulty providing accurate responses to Schedule 2. In addition, the data collected on certain minor and self-produced fuels (blast furnace gas, other manufactured gases, kerosene, propane, jet fuel, and waste oils) is difficult to verify and edit because the quality and pricing are inconsistent and volatile. Based on this experience EIA proposes the follows changes, intended to reduce EIA’s data processing burden and respondent burden:
Raise the schedule 2 reporting threshold to 200 MW of nameplate capacity for plants fueled by natural gas, petroleum coke, distillate fuel oil, and residual fuel oil. Based on comments EIA received in response to the 60-day Federal Register Notice, the reporting threshold will not be raised for coal-fired power plants (see Part A, Appendix A-1).
Remove the reporting requirement for self-produced and minor fuels.
Statistical estimation of non-sampled entities will no longer be performed for published data from Schedule 2 of the Form EIA-923. (Statistical imputation for non-responding entities sampled, if any, will continue to be performed.)
B.1. Respondent1 Universe and Target Population
B.1.1. Form EIA-861, "Annual Electric Power Industry Report"
The Form EIA-861, "Annual Electric Power Industry Report,” has historically been a census of participants in the electric power industry primarily involved in the distribution and sale of electric energy in the United States and its territories. Target population members include electric utilities, wholesale power marketers (registered with the Federal Energy Regulatory Commission), energy service providers (registered with the States), and electric power producers who make retail sales of electricity. Responses are collected at the business (operating) level.
This population comprises approximately 3,300 entities, primarily electric utility companies. This survey serves as the universe from which the sample for the Form EIA-826 is drawn (discussed further below).
EIA is proposing to modify this survey from a census to a cutoff sample of approximately 2,200 entities. The remaining 1,100 utilities would report a limited set of data on a new short form survey, discussed immediately below.
B.1.2. Form EIA-861S, "Annual Electric Power Industry Report (Short Form)"
EIA is proposing to create the new Form EIA-861S. The Form EIA-861S has been designed for the approximately 1,100 respondents that would be removed from the Form EIA-861, based on certain characteristics. The Form EIA-861S will be completed by all electric utilities with annual retail sales in the prior year of 100,000 megawatthours (MWh) or less, with the following exceptions: 1) the respondent has retail sales of unbundled service; 2) the full set of data is required from the respondent to ensure that statistical estimates for a State or business sector are of acceptable quality; 3) the respondent instead reports in aggregate under the Tennessee Valley Authority (TVA) or WPPI Energy; 2 and 4) the company is part of the sample for the Form EIA-826, "Monthly Electric Utility Sales and Revenue Report with State Distributions” (discussed below). Utilities for which any of these exceptions apply will complete the regular (long) version of the Form EIA–861 survey.
Note that respondents can only complete one type of Form EIA-861: either the Form EIA-861 or the Form EIA-861S, but not both. Responses are collected on both types of forms at the business (operating) company level.
The Form EIA-861S will collect a limited set of data including retail sales, revenue, and customer counts by State for each operator. The division of this data by industry sector (residential, commercial, industrial, and transportation) will be performed by statistical estimation, as discussed in B.2.
In order to maintain the accuracy of the estimation procedure associated with the Form EIA-861, once every 5 years the Form EIA-861S respondents will be required to fill out the Form EIA-861.
B.1.3. Form EIA-826, "Monthly Electric Utility Sales and Revenue Report with State Distributions”
Note: This clearance does not involve any revisions to the Form EIA-826 survey. It is discussed here only because the sample for this survey is drawn from respondents to the Form EIA-861 survey, the frame for which would change.
The Form EIA-826 is a monthly survey of a sample of electric power entities, distributors, and retailers. The survey collects information on retail electric sales and revenue by operating company, customer class, and State. The data are the monthly equivalent to the annual data reported on the Form EIA-861. Statistical imputation is used to estimate State and national totals.
The Form EIA-826 takes its sample from the universe of respondents on the annual Form EIA-861 and imputes for the other approximately 2,800 members of the universe. Cutoff sampling is used to select the sample, which includes most of the investor-owned utilities (160, including all distribution companies with unbundled electricity sales), four Federal utilities, all electric service providers (150), and a sample of 194 municipal, cooperative, State and political subdivision utilities that have sales to end-use customers.
There will be no sampling changes to the Form EIA-826 and all entities collected on the Form EIA-826 will remain in the Form EIA-861 sample.
B.1.4. Form EIA-923, "Power Plant Operations Report”
The target population for this survey comprises all electric plants in the United States that are connected to the electric power grid and have a generating capacity of 1 megawatt or greater. While the target population is defined in terms of plants, the respondents for the Form EIA-923 are companies, which report data for the eligible plants they operate. There are approximately 5,600 operating power plants (being reported by 2,800 respondents) for which data are collected through Form EIA-923.
The survey collects data on fuel receipts, consumption, electric generation, fuel stocks, combustion byproducts, operational cooling water data, and operational data for NOx, SO2, and particulate matter control equipment. Not all respondents answer all questions; for example, questions on fuel consumption are inapplicable to hydroelectric, wind, and certain other types of power plants.
As part of this clearance, EIA is proposing to reduce the respondent group that currently reports on the characteristics of purchases of combustible fuels, such as coal and natural gas.3 These data are reported on “Schedule 2: Cost and Quality of Fuel Purchases.” The proposed changes are described in the summary section of this Part B and in detail in Part A. If approved, these changes will reduce natural gas data collection on Schedule 2 from approximately 1,339 to 603 plants with a reduction of approximately 9 percent of natural gas purchases, cost, and quality data. Petroleum (including petroleum coke) data collection on Schedule 2 will be reduced from approximately 160 to 57 plants with a reduction of approximately 22 percent of petroleum and petroleum coke purchases, cost, and quality data. Additionally, 35 plants will no longer be required to report purchases of blast furnace gas, other manufactured gases, kerosene, jet fuel, propane, and waste oil. There is no change to the coverage of coal-fired plants for the reasons discussed in Part A, Appendix A-1.
B.2. Statistical Methodology for Sampling and Imputation
B.2.1. Forms EIA-861 and EIA-861S
Respondents to the existing Form EIA-861 survey report their total electricity sales (MWh), revenue (thousands of dollars), and number of customers. The respondents also report how each of these data items is divided by customer class (residential, commercial, industrial, and transportation). In contrast, respondents to the proposed Form EIA-861S will only report their total electricity sales, revenue, and customers count. For these respondents, EIA plans to use statistical imputation to allocate the totals to customer classes.4
EIA has researched cutoff model-based estimation (Knaub, 1999)5 and uses it for the Form EIA-826 survey process. A methodology similar to that currently applied to estimate for out-of-sample entities monthly for the Form EIA-826 will be applied to out-of-sample entities for the Form EIA-861 who will receive the Form EIA-861S. Specifically, EIA proposes to estimate the allocation of sales, revenue and number of customers by sector using a weighted least squares regression model. Out-of-sample observations will be estimated using a prior year’s data as regressor data.
As proposed by EIA, every 5 years the respondents to the Form EIA-861S short form will be required to complete the full Form EIA-861 survey. This means that for 4 out of every 5 years, the imputation process will be based on “old” data; i.e., the last complete census of the respondent universe. A concern is therefore whether the use of older data will lead to a material degradation of the quality of the estimates published by EIA. EIA has studied this issue and found that for the data elements of concern, five-year old regressor data can be used to estimate for current year’s data.
Table 1 results show relative standard error (RSE) estimates using 2004 Form EIA-861 regressor data to estimate 2009 sales and revenue data by economic end-use sector and region when the 1,100 respondents are eliminated from the sample. RSE estimates are designed as performance measures regarding sampling error. Correlation between current Form EIA-861 sales and revenue data and 5-year old Form EIA-861 sales and revenue data, respectively, is very high. Thus Form EIA-861 data collected only at intervals on the entire population can work well as regressor data for a new non-censused Form EIA-861 data set, as well as for the Form EIA-826 data monthly, as long as the frame is maintained.
Table 1. Retail Sales and Revenue Relative Standard Error Estimates (%) using 2004 Regressor Data
|
SALES |
|
REVENUE |
||||||||
REGION |
RES |
COM |
IND |
TRANS |
TOTAL |
|
RES |
COM |
IND |
TRANS |
TOTAL |
EAST_NORTH_CENTRAL |
0.04 |
0.04 |
0.09 |
0.13 |
0.04 |
|
0.05 |
1.80 |
0.33 |
1.35 |
0.66 |
EAST_SOUTH_CENTRAL |
0.04 |
0.05 |
0.06 |
0.00 |
0.03 |
|
0.05 |
0.06 |
0.07 |
0.00 |
0.03 |
MIDDLE_ATLANTIC |
0.19 |
0.07 |
0.39 |
0.01 |
0.10 |
|
0.17 |
0.91 |
0.34 |
0.01 |
0.43 |
MOUNTAIN_REGION |
0.07 |
0.04 |
0.14 |
0.00 |
0.05 |
|
0.09 |
0.06 |
0.12 |
0.00 |
0.05 |
NEW_ENGLAND |
0.08 |
0.08 |
0.20 |
0.16 |
0.06 |
|
0.08 |
1.25 |
0.16 |
2.79 |
0.50 |
PACIFIC_CON |
0.03 |
0.02 |
0.16 |
0.00 |
0.03 |
|
0.17 |
0.16 |
0.29 |
0.00 |
0.11 |
PACIFIC_NON_CON |
0.20 |
0.27 |
0.32 |
0.00 |
0.16 |
|
0.25 |
0.30 |
0.25 |
0.00 |
0.16 |
SOUTH_ATLANTIC |
0.05 |
0.04 |
0.09 |
0.00 |
0.03 |
|
0.06 |
0.07 |
0.12 |
0.79 |
0.04 |
WEST_NORTH_CENTRAL |
0.10 |
0.08 |
0.16 |
0.00 |
0.07 |
|
0.15 |
0.17 |
0.23 |
0.00 |
0.10 |
WEST_SOUTH_CENTRAL |
0.05 |
0.56 |
0.15 |
0.00 |
0.20 |
|
0.05 |
0.60 |
0.14 |
0.00 |
0.21 |
USA |
0.03 |
0.08 |
0.05 |
0.02 |
0.03 |
|
0.04 |
0.30 |
0.08 |
0.21 |
0.11 |
B.2.2. Form EIA-826
Cutoff model-based estimation is used to estimate sales, revenue and number of customers by State and sector for out-of-sample respondents monthly for Form EIA-826 (Knaub, 1999). Previously, Form EIA-861 data has been used as regressor data to estimate for these monthly out-of-sample observations using a weighted least squares regression model. The sampling estimation methodology used to estimate for out-of-sample respondents for the Form EIA-826 will remain un-changed in the first revisionary year, because EIA will retain a census of Form EIA-861 data. In subsequent years, EIA proposes to use one to five year old regressor data. As discussed above, EIA has studied if it is possible to use older Form EIA-861 regressor data to estimate for current Form EIA-826 monthly data and these efforts have proven to be effective.
B.2.3. Form EIA-923
EIA is proposing to reduce the respondent group that currently reports on “Schedule 2: Cost and Quality of Fuel Purchases.” Respondents will be required to provide this information for coal-fueled plants with as nameplate capacity of 50 megawatts and above, and for other power plants with a capacity of 200 megawatts and above. EIA will not estimate data on Schedule 2 for out-of-sample respondents. The data will be reported with this coverage limitation noted.
B.3. Methods to Maximize Response Rates
For all of the EIA electric power surveys, the response rates are close to or equal to 100 percent. To maximize response rates, the EIA forms have been designed and the instructions have been written to be clear and concise to help the respondent complete the forms. Data that are not expected to change from year-to-year or month-to-month are pre-populated on the forms. Forms and/or notifications are emailed early to maximize the time that respondents have to complete the surveys.
As noted in Part A, EIA’s Internet data collection system makes forms available on-line as soon as respondents obtain a secure ID and password. Given the high Internet use rate (approximately 95 percent), most online respondents will log on in the next data collection period and access their required forms. Form due dates are the same each period so that respondents can schedule their completion activities.
Any non-respondents are contacted by email, telephone, and letter to request data submission, until an insignificant or zero non-response rate is obtained. Follow-up emails citing failure to file the required form are sent to all non-respondents. If the follow-up emails do not result in a response, additional correspondence requesting immediate submission is sent to the supervisor of the primary contact and, if necessary, to higher-level management officials at the non-respondent entity. These letters are sent from the Office Director or, if necessary, from the EIA Administrator.
Respondents who file via the Internet system are given the opportunity to either correct or explain unusual data during their submission. The explanations are reviewed by the EIA staff. Respondents are contacted if further clarification is needed. For those respondents that do not file via the Internet, but rather on a hard copy of the form, email and/or telephone calls are made to confirm corrections or clarifications of any suspicious data.
Changes in plant ownership and/or contacts have contributed in the past to non-response. To address this issue, EIA has developed an improved centralized frame system for the electric power surveys, which affords all survey staff almost immediate knowledge of changes in entity ownership and/or contacts. This frame system is integrated with the Internet system so that access can quickly be given to new owners and/or contacts.
B.4. Tests of Procedures
The Forms EIA-861 and EIA-923 (including Schedule 2) were subject to full review when the surveys went through the regular three-year clearance process in 2010. The electric power surveys are established continuing surveys, and testing was performed at the time the surveys were being established.6 The proposed revisions to the surveys result in minimal changes to the survey forms, as illustrated by the markups of the forms accompanying this supporting statement.
The Form EIA-861S is a new short form based on the Form EIA-861. The survey was developed with the assistance of EIA’s in-house design experts and also made available as part of the 60-day Federal Register Notice process for public review.
B.5. Forms Consultation
EIA contacted a variety of electric power industry participants to make them aware of the proposals for the Forms EIA-861 and EIA-923 survey form changes and to elicit their suggestions, concerns, and needs. All of the current respondents were contacted along with the following stakeholders:
American Council for an Energy Efficient Economy
American Public Power Association
American Statistic Association
American Wind Energy Association
DOE, Office of Electricity Delivery and Energy Reliability
DOE, Office of Fossil Energy
Edison Electric Institute
Electricity Consumers Resource Council
Electricity Storage Association
Electric Power Supply Association
U. S. Environmental Protection Agency
Federal Energy Regulatory Commission
National Association of Regulatory Utility Commissioners
National Association of State Utility Consumer Advocates
National Hydropower Association
National Mining Association
National Rural Electric Cooperative Association
Natural Resources Defense Council
North American Electric Reliability Corporation
Ocean Renewable Power Company
Ozone Transportation Commission
Platts
Science and Technology Policy Institute
Solar Energy Industries Association
Interested parties were also notified of the proposed changes via the 60-day Federal Register Notice (FR Vol. 77, No. 51, pg. 15362, published on March 15, 2012) and a press release on April 9, 2012 sent to an email list of over 10,000 subscribers. For a summary of the comments received and EIA’s response see Part A, Appendix A-1.
As discussed in Part A of this supporting statement, based on comments received the following changes were made to the original proposal:
The Form EIA-861S will collect retail revenues and customer counts in addition to retail sales (MWh).
On Schedule 2 of the Form EIA-923, the 50 MW reporting threshold will not be raised for plants where the primary fuel is coal.
For additional information concerning these surveys, please contact Rebecca A. Peterson at 202-586-4509 or at [email protected].
For information concerning this request for OMB approval, please contact the agency Clearance Officer, Alethea Jennings, at (202) 586-5879, or [email protected].
Appendix B-1: Part B of the Original Clearance Package Supporting Statement, September 2010
Part B
Collection of Information Employing Statistical Methods
B.1. Respondent7 Universe
The electric power surveys collectively cover the entire range of companies involved in the generation, transmission, distribution, and sales of electricity. Of the six surveys in this package, three surveys are of the entire universe (or nearly the entire universe) based on more exacting filing requirements given in those surveys; a fourth survey is for additional information as it becomes available. A fifth survey has both an annual census and a monthly sample component; and a sixth survey is a monthly sample survey corresponding to one of the annual census surveys. The respondent frame for each survey is:
Form EIA-411 – The target population for this annual census comprises all electricity generators and electric utilities in the United States. The eight Regions of the North American Electric Reliability Corporation (NERC) collect the data from the target population units. Each Region assembles the required information using input from the member electricity generators and electric utilities in its geographic area. The Regions submit the compiled data to the NERC headquarters, where it is consolidated and forwarded to the EIA.
Form EIA-826 – The target population for this monthly survey comprises all U.S. electric utilities, electric service providers, and distribution companies. Cutoff sampling is used to select the sample for the Form EIA-826, which includes most of the investor-owned utilities (188), 4 Federal utilities, all electric service providers (92), all distribution companies, and a sample of approximately 164 municipal, cooperative, State and political subdivision utilities that have sales to end-use customers.
Form EIA-860 – The target population for this annual census comprises all existing and proposed (for operation within 5 years) electric power plants that have a total generator nameplate capacity of 1 megawatt or greater. Companies complete the form for all the plants they operate. There are approximately 2,700 entities that operate and/or propose to operate about 5,800 facilities, containing over 19,000 generators, who are required to file the Form EIA-860. The respondents to this survey form the basis of the EIA electric power entity frame, from which samples for other surveys are drawn.
Form EIA-860M – The target population for this monthly census comprises power plants within the EIA-860 target population that have either (a) a new generator scheduled to begin commercial operations within the next 12 months, or (b) an existing generator scheduled for retirement within the next 12 months, or (c) an existing generator undergoing modifications resulting in changes in capacity or other major modifications that are scheduled to be completed within 1 month. Respondents are the operators of the power plants where these new generators and existing generators are located. Based on the number of plants putting new generators into service in 2008 and 2009, the EIA estimates that in a typical month the Form EIA-860M will be used to collect data from approximately 124 respondent entities.
Form EIA-861 – The target population for this annual census comprises participants in the electric power industry involved in the generation, transmission, or distribution of electricity in the United States and its territories. Target population members include electric utilities, wholesale power marketers (registered with the Federal Energy Regulatory Commission), energy service providers (registered with the States), and electric power producers. There are approximately 3,300 entities in the United States involved in the generation, transmission, and distribution of electric energy. This survey serves as the universe from which the sample for the Form EIA-826 is drawn.
• Form EIA-923 – The target population for this annual census comprises all electric plants in the United States that are connected to the electric power grid and have a generating capacity of 1 megawatt or greater. While the target population is defined in terms of plants, the respondents for the Form EIA-923 are companies, which report data for the eligible plants they operate. There are approximately 5,573 operating power plants (being reported by 2,800 respondents) for which data will be collected through Form EIA-923. Data will be reported monthly for a sample of approximately 1,781 plants, although this may be adjusted as the data are evaluated. Monthly respondents will report on Schedules 1, 3, 4, and 5, plus Schedule 2 if they have a fossil-fueled capacity of 50 megawatts or greater. At the end of the year, the monthly respondents will report on Schedules 6 and 7, plus Schedule 8, if they have a steam-electric organic-fueled capacity of 10 megawatts or greater. Those respondents who are not in the monthly frame will file annually. They will file Schedules 1, 3, 4, 5, 6, and 7, plus Schedule 2 if they have a fossil-fueled capacity of 50 megawatts or greater and Schedule 8, if they have a steam-electric organic-fueled capacity of 10 megawatts or greater.
B.2. Statistical Methodology
To limit the burden on industry respondents, two of the monthly surveys, the Form EIA-826 and the Form EIA-923, are sent to only a sample of units in the target populations. The samples are cutoff samples, i.e., they are basically comprised of all units with measures of size larger than a predefined threshold. This is complicated by compromises due to the need for data on multiple variables of interest. The cutoff sampling eliminates the monthly reporting burden for smaller industry participants. Because smaller units have, in the past, been responsible for a high percentage of reporting errors, the cutoff sampling may also reduce the levels of non-sampling error affecting the published estimates. (See Knaub (2007, 2008) on cutoff sampling in general, Royall (1970) on model variance, and Knaub (2001) on model bias and variance.) The remainder of this section provides detail on the sampling and estimation methods used for the two sample surveys.
Form EIA-826 Sampling
For the Form EIA-826, the sample is composed of those utilities that typically sell most of the electricity in each category (or end-use sector) in each State. The sample is made up of:
All investor-owned utilities (IOUs), except for a few small IOUs in Alaska
All energy service providers
All Federal utilities
All entities selling in the public transportation sector
A sample of the municipal and cooperative utilities.
The frames for Schedule B (energy service providers) and Schedule C (distribution companies) are not always complete, as information from the States on these entities is not always available in a timely manner. In these cases, the two types of respondents are reconciled at the State level and added to the State totals. (Classical ratio estimation can be used for variance estimation. See Knaub (1991), pages 776 and 777, “Incompletely Specified Auxiliary Data.”) A zero-intercept, ratio model (see Royall and Cumberland, 1978) is used to estimate total sales and revenue by end-use sector and State. The sample eliminates the smaller respondents, thus reducing burden and reducing the source of non-sampling errors.
The Form EIA-826 sample design and estimation procedures employ a linear regression model to represent the relationship between the respondent’s annual data value (e.g., sales) from the prior year and the corresponding monthly value for the current month. The prior year’s annual data come from the Form EIA-861. Data values for units not in the sample are estimated from the prior year’s annual data and the estimated parameters of the regression model. Data from sample units for which there is no historical Form EIA-861 data (e.g., units new to the target population) are not used to estimate the relationship between the prior year’s annual value and the current monthly value. The reported current monthly data are, however, used in estimating totals for publication groups. (See Knaub (2002).) If a sample unit’s annual data are deemed reliable, and its Form EIA-826 (monthly) data are considered unreliable, the annual data are used (as for the non-sampled units) to impute the monthly Form EIA-826 data. As mentioned above, a census is performed within the Form EIA-826 for the power marketers or energy service providers (ESP) data, and their totals are added to the estimated (imputed) entities to obtain the estimates for the entire universe.
Form EIA-826 Monthly Sample Selection from the Form EIA-861 Annual Frame
The monthly cutoff sample thresholds for the Form EIA-826 were originally selected based on the criterion of having estimated relative standard error (RSE) values less than 1 percent for all publication groups. The RSE is a percentage measure of the precision of a survey statistic and is used in part as one way to measure sampling error induced by sampling. RSEs are estimated to account for using model-based predicted monthly values in place of missing and non-sampled data for the quantities of interest (revenues, sales, etc.), based on monthly sampled data from the Form EIA-826, and the corresponding annual (Form EIA-861) data for the units not in the monthly sample. Threshold values for the cutoff sampling have been adjusted over time to maintain low RSEs for the published estimates.
Form EIA-923 Sampling
One of the goals of the original Form EIA-923 sample selection process was to reduce the sample size from the separate predecessor Forms EIA-906 and EIA-920. Not only did this reduce respondent burden, but it also allowed the EIA survey staff to focus its resources on a smaller sample to ensure a higher quality of data. A reduction in sample size was deemed especially important in the commercial and industrial sectors due to sometimes questionable data quality and the difficulty in collecting data from many of the smaller facilities. This original goal continues to be an important focus of attention of the ongoing Form EIA-923 sampling strategy (See Douglas (2007)).
The cutoff sampling process for the Form EIA-923 sample is similar to the one described above for the monthly Form EIA-826 sample. Since the original Form EIA-923 sample was established with the 2008 data collection cycle, it is estimated that 261 plants will have been added to the monthly sample to maintain the targeted sample coverage ratios by the inception of the 2011 data collection cycle. These sample additions are deemed necessary as large currently planned and under construction plants become operational. Ongoing sample validation studies may produce other necessary sample additions as needed.
Gross generation was the main focus of the original sample selection process and its high correlation with other data elements on the Form EIA-923 ensured good coverage results for other reported values. Since then, sample validation studies were conducted on fuel consumption, receipts, costs and stocks and the sample was adjusted accordingly.
Sampling parameters are assigned to each sampling stratum. The strata are defined by facility type, energy source, and geographic region. (See "publication groups" in Knaub (1999).) For instance, one stratum is identified as electric utilities burning coal in the South Atlantic Census Division. The types of stratification groups are briefly described below.
Facility Type Classification for Form EIA-923
The four facility type categories comprise seven sectors for which data are collected. These four categories, which correspond to the facility type classifications published in the Electric Power Monthly (EPM), are (1) electric utilities, (2) independent power producers, (3) commercial facilities, and (4) industrial facilities. Table 8 below shows the seven sectors. (Combined Heat and Power Plant is abbreviated CHP.)
Table 8. Facility Types
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Energy Source Classification for Form EIA-923 |
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The 14 energy source categories, which correspond to the energy source classifications published in the EPM, are aggregations of the 36 different fuel types for which data are collected on the survey. Table 9 gives the 14 energy source categories and the corresponding stratification categories. The energy source codes are defined in the instructions for completing Form EIA-923. (See Appendix C.)
Table 9. Energy Source Aggregations
Geographic Regions Classification for Form EIA-923
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The 10 geographic sampling groups correspond to 10 modified Census division regions published in the EPM. The States assigned to each division are shown in Table 10.
Table 10. State/Census Division Aggregations
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Original Sample Selection Criteria for Form EIA-923
The Form EIA-923 sample was chosen to provide reasonably accurate results for multiple attributes (published aggregate numbers) while minimizing the burden on the industry and the Federal government. The following five steps were used in selecting plants for the monthly sample:
Select preliminary cutoff samples based on nameplate capacity values
Add sample units, where necessary, based on generation, consumption and stocks
Add sample units, where necessary, to provide adequate sample counts for estimation groups
Add sample units, where necessary, to reduce relative standard errors (RSEs) of key estimates to acceptable levels
Add other facilities, based on special-case criteria.
The first three steps were designed to ensure adequate coverage of the target population by including all of the largest contributors to key data elements. The fourth step helps ensure that the published estimates meet reasonable reliability standards, which is the key goal, given acceptable resource expenditure. The final criterion covers special cases, as described below.
Facilities in the target population that meet any one of the sample selection criteria applied at any of the five steps were included in the final sample. Further, any additional prime movers and energy sources used by a sample facility were also included in the sample even if individually they did not meet any of the sample selection criteria. Each sample facility reports data for all combinations of prime mover and fuel source each month. All nuclear and pumped storage facilities are included in the monthly sample. The remainder of this section provides further detail on the sampling steps.
Step 1: Select Cutoff Samples Based on Nameplate Capacity. Initially, pre-determined capacity coverage percentages were tested to ensure a certain proportion of operational Form EIA-860 capacity is covered within each sampling group. Stand-by and back-up generators were not included in the operational capacity totals when data were aggregated to the level of prime mover, and only the largest consumed fuel source for each generator were used in identifying the sample groupings. Different target coverage percentages were selected for each facility classification, and were applied to all regions and energy sources within each classification. When the capacity cutoff percentage yields a capacity cutoff of less than 25 megawatts, then a default value of 25 megawatts was used instead. Otherwise, the percentages of capacity included in the sample are listed below.
Electric utilities – 70 percent
Independent power producers – 70 percent
Commercial facilities – 50 percent
Industrial facilities – 50 percent.
Step 2: Add Units Based on Generation, Consumption, and Stocks. Facilities accounting for large percentages of actual past reported gross generation, fuel consumption, or fuel stocks, were added to the sample, even if their nameplate capacities fell below the capacity coverage percentage cutoff.
Step 3: Add Units to Ensure Adequate Sample in Estimation Groups. Estimation strata identical to those employed in the Form EIA-923 regression imputation system were examined. Units below the threshold value were added to any group with fewer than 10 usable observations, until the usable count was brought up to 10.
Step 4: Add Sample to Meet Reliability Standards. Weighted multiple regressions, identical to those currently employed in the Form EIA-923 imputation system, were run, and relative standard error (RSE or CV) estimates were calculated for each publication group by month. An additional diagnostic measure, the relative standard error for a superpopulation (RSESP) was calculated to indicate the adequacy of the regression model fit. Limits for both measures (RSE and RSESP) were set individually for each facility classification and applied to all energy sources for the U.S. total for each classification.
If one or both of the error measures fell outside of the limits, the next largest facilities, ranked by gross generation, were included until the RSE/RSESP's were brought into a reasonable range. It is important to note that if only the RSESP estimate was out of range, then it was difficult to lower the estimate of RSESP based on sampling alone. In these cases, a change in modeling may be necessary. The RSE/RSESP data quality limits are outlined below.
Electric utilities – RSE less than 5 percent and RSESP less than 20 percent
Independent power producers – RSE less than 5 percent and RSESP less than 20 percent
Commercial facilities – RSE less than 10 percent and RSESP less than 30 percent
Industrial facilities – RSE less than 10 percent and RSESP less than 30 percent.
Step 5: Add Special Cases. Finally, additional facilities were added to the sample as necessary. These include storage-only facilities (used in estimating stocks); new facilities for which the EIA has no prior-year’s annual data for use in regression imputation; and any large, easy to survey facilities which the survey staff identified as being desirable in the sample.
Table 11 shows the sample coverage by facility type and Table 12 shows the sample coverage by energy source.
Table 11. Form EIA-923 Sample Coverage by Facility Type
Table 12. Form EIA-923 Sample Coverage by Energy Source
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REFERENCES:
The regression estimation/imputation procedures used for the Form EIA-826 and Form EIA-923 are documented and discussed in the on-line statistics journal, InterStat, in the following articles:
The method described in these articles is generally useful for both small area estimation and imputation, with adjustments as described in those documents. Additional documentation and references include:
(1) “Model-Based Sampling, Inference and Imputation,” available on the EIA Web site at: http://www.eia.doe.gov/cneaf/electricity/forms/eiawebme.pdf
(2) “Weighting in Regression for Use in Survey Methodology," InterStat, available at: http://interstat.stat.vt.edu/InterStat/ARTICLES/1997/abstracts/A97001.html--ssi. (3) “Some Applications of Model Sampling to Electric Power Data,” ASA Proceedings of the Survey Research Methods Section, available at:www.amstat.org/sections/SRMS/proceedings/papers/1991_133.pdf
(4) Royall, R.M., and W.G. Cumberland (1978), "Variance Estimation in Finite Population Sampling," Journal of the American Statistical Association, 73, 351-358
(5) “The Classical Ratio Estimator,” InterStat, available at: http://interstat.statjournals.net/YEAR/2005/abstracts/0510004.php
(6) “Cutoff Sampling and Inference,” InterStat, available at: http://interstat.statjournals.net/YEAR/2007/abstracts/0704006.php.
(7) “Cutoff vs. Design-Based Sampling and Inference For Establishment Surveys,” InterStat, available at: http://interstat.statjournals.net/YEAR/2008/abstracts/0806005.php?Name=806005
(8) Douglas, Joel R.(2007), “Model-Based Sampling Methodology for the new EIA-923,” Presented to the American Statistical Association and EIA’s Joint Meeting on Energy Statistics, October 18, 2007, http://www.eia.doe.gov/smg/asa_meeting_2007/fall/files/modeleia923.ppt.
B.3. Methods to Maximize Response Rates
For all of the EIA electric power respondents, the response rates are close to or equal to 100 percent. For 2008 annual data, all 11,117 annual respondents (aggregated across all surveys) submitted their data and typically only about 3-7 out of 2,252 monthly 2009 data respondents did not submit their data in any given month. To maximize response rates, the EIA forms have been designed and the instructions have been written to be clear and concise to help the respondent complete the forms. Data that are not expected to change from year-to-year or month-to-month are pre-populated on the forms. Forms and/or notifications are mailed or emailed early to maximize the time that respondents have to complete the surveys. As noted, the EIA Internet Data Collection (IDC) System makes forms available on-line as soon as respondents obtain a secure ID and password. Given the high IDC use rate in 2009 (approximately 95 percent of the monthly reports and an estimated 90 percent of the annual reports), most of those respondents will merely log on in the next data collection period and access their required forms. Form(s) due dates are the same each period so that respondents can schedule their completion activities. The notification and due dates for each survey are provided in Table 6.
The non-respondents are contacted by email, telephone, and letter to request data submission until an insignificant non-response rate is obtained. Follow-up letters and emails citing failure to file the required form are mailed to all non-respondents. If no response occurs as a result of the letters, additional correspondence, requesting immediate submission of the appropriate data, is sent to the supervisor of the primary contact and, if necessary to higher-level management officials at the non-respondent entity. These letters are sent from the Office Director or, if necessary, from the EIA Administrator. Statistical imputation fills any gaps created by the small amount of non-response.
Respondents who file via the IDC System are given the opportunity to either correct or explain unusual data during their submission. The explanations are reviewed by the EIA staff. Respondents are called if further clarification is needed. For those respondents that do not file via the IDC, but rather on a hardcopy of the form, telephone calls are made to confirm corrections or clarifications of any unusual data.
In addition, the EIA has recently developed an improved centralized frame system which affords all survey staff almost immediate knowledge of changes in plant ownership and/or contacts; such changes contributed to non-response in the past. The new system is integrated with the IDC System so that access can be given to new owners and/or contacts quickly. |
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1 Respondents refer to entities in a survey frame.
2 TVA and WPPI Energy (the latter a consortium of public power utilities in the Midwest) consolidate responses for their wholesale customers and deliver the information to EIA. Extracting a subset of utilities from the joint filings of TVA and WPPI would be administratively cumbersome and would defeat the purpose of the proposed change to the Form EIA-861 frame, which is to reduce the cost of managing the survey for both EIA and respondents.
3 It is important to distinguish the fuel receipts data collected on Schedule 2 of the Form EIA-923 from the fuel consumption data and as-burned fuel quality data collected on other schedules of the survey. There will no change to the coverage of these other schedules. For additional information see Part A of the supporting statement.
4 In practice, few if any respondents to the Form EIA-861S will have retail sales to the transportation sector (mass transit systems and electrified inter-city rail) so the issue is using statistical imputation to allocate between the residential, commercial, and industrial sector.
5 Knaub, J.R., Jr. (1999), “Model-Based Sampling, Inference and Imputation,” http://www.eia.gov/cneaf/electricity/forms/eiawebme.pdf
6 EIA’s policy is to test in several phases. First, the proposed forms are reviewed by internal EIA subject matter and survey methodology experts. The second phase of this testing involves sending draft forms to representatives of the major segments of the electric power industry. Finally, the proposed forms are tested with actual volunteer survey respondents. These respondents are asked to review the forms, and then they are debriefed by EIA to make sure they understand the concepts being measured, can successfully navigate the forms, and have the response data in their business records. Changes are made at all stages of testing to incorporate feedback.
7 Respondents refer to entities in a survey frame.
8 Pumped Storage facilities do not actually report energy source code HPS, rather they report energy source code WAT combined with a prime mover code of PS to differentiate them from conventional hydroelectric facilities. The energy source is renamed to HPS for simplicity sake only.
| File Type | application/vnd.openxmlformats-officedocument.wordprocessingml.document |
| Author | Rebecca McNerney |
| File Modified | 0000-00-00 |
| File Created | 2021-01-30 |
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