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CBECS Home Page 1. How the Survey Was Conducted:
Return to: 1995 Detailed Tables |
Building Characteristics Survey Building Eligibility Determining building eligibility was a three-step process. The first step occurred during the development of the area and supplemental sample listings. The second step occurred when the interviewer observed the building, and the third step occurred during the interview of the building owner or manager. While criterion one, the definition of a building, can be determined during the first and second steps, criteria two and three are based more on lister or interviewer judgment and could result in exclusion of eligible buildings or the inclusion of ineligible buildings during those steps. The third step is crucial in identifying ineligible buildings. Once the interviewer begins the interview, initial screening questions instruct the interviewer to terminate the interview if criterion two or three is not met. Criterion 1—Building Definition: The definition of a building was the same one used in previous CBECS: a structure totally enclosed by walls that extend from the foundation to the roof and intended for human access. Thus, structures such as water, radio, and television towers were excluded from the survey. Also excluded were (1) parking garages and partially open structures, such as lumber yards; (2) enclosed structures that people usually do not enter or are not buildings, such as pumping stations, cooling towers, oil tanks, statues, and monuments; and (3) dilapidated or incomplete buildings missing a roof or a wall. There is one exception to the building definition criterion: a structure built on pillars so that the first fully enclosed level is elevated. These were included because such buildings fall short of meeting the definition due only to the technical shortcoming of being raised from the foundation. They are totally enclosed, are used for common commercial purposes, and use energy in much the same way as buildings that sit directly on a foundation. Criterion 2—Building Use: The second criterion was that a building had to be used primarily for some commercial purpose; that is, more than 50 percent of the building’s floorspace must have been devoted to activities that were neither residential, industrial, nor agricultural. The primary use of the sampled building governed whether the building was included in the CBECS. In 1995, there was one exception to this criterion: commercial buildings on manufacturing sites were considered out of scope. (In previous CBECS, if a commercial building (e.g., an office building), was located on a manufacturing site, it would have been considered in scope). Examples of nonresidential buildings that were not included in the CBECS samples are: Farm buildings, such as barns, unless space is used for retail sales to the general public Industrial or manufacturing buildings that involve the processing or procurement of goods, merchandise, or food Buildings on most military bases Buildings where access is restricted for national security reasons Single-family detached dwellings that are primarily residential, even if the occupants use part of the dwelling for business purposes Mobile homes that are not placed on a permanent foundation (even if the mobile home is used for nonresidential purposes). During the interviewing stage, interviewers were instructed not to begin interviews at buildings where they observed that 75 percent or more of the floorspace was used for residential, industrial, or agricultural purposes. Once the interview began, screening questions instructed the interviewer to terminate the interview if the respondent indicated that 50 percent or more of the square footage was used for residential, industrial, or agricultural purposes. Criterion 3—Building Size: The third criterion was that a commercial building had to measure more than 1,000 square feet (about twice the size of a two-car garage) to be considered in scope for the 1995 CBECS. This building size criterion was met in two successive size cutoffs, which were enacted during the listing and interviewing processes. During the listing stage, buildings judged to be less than 500 square feet were not listed. Interviewers did not begin interviews when they observed a building to be 500 square feet or less. Then during the interviewing stage, interviewers asked screening questions designed to terminate the interview when the square footage was reported to be 1,000 square feet or less. Data Collection Data collection encompasses several phases, including: (1) designing the questionnaire, (2) training supervisors and interviewers, (3) collecting data, (4) minimizing nonresponse, and (5) processing the data. A survey contractor performed the data collection under the direction of EIA. Designing the Building Characteristics Survey Questionnaire Questionnaire design work for the 1995 CBECS was conducted by EIA. Although a set of core questions remained the same or very similar to those used in previous surveys, the 1995 Building Questionnaire was redesigned to improve data quality and to allow the data to be collected by use of Computer-Assisted Personal Interviewing (CAPI) techniques. Training Supervisors and Interviewers The CBECS building questionnaire is a complex instrument designed to collect data during a personal interview at the building site. Well-trained interviewers are imperative to the collection of technical information. Training for the 1995 CBECS included three in-person training sessions: one session for the interviewer trainers, monitors, and regional supervisors and two sessions for the interviewers. Because the 1995 CBECS was collected for the first time by using CAPI, all interviewers were trained in the general use of the computer and in interviewing and administering the CAPI questionnaire. Training sessions included lectures, interviewers slide presentations, and small group sessions where the interviewers practiced administering the questionnaire by using laptop computers. EIA personnel participated in all training sessions, providing an overview of the CBECS and a presentation on the key 1995 CBECS energy concepts. Collecting the Data Initial contacts with the building representatives were made through an introductory letter mailed to them at each building or facility in the survey sample. The letter, signed by a representative of EIA, was addressed to the building owner or manager. The letter explained that the building had been selected for the survey, introduced the survey contractor, assured the building manager that the data would remain confidential, and discussed the uses and needs for the CBECS data in setting national energy policies. To protect confidentiality, the letter was addressed by the survey contractor after it was signed at EIA. A worksheet was attached to the letter that listed several pieces of information that the respondent should have ready for the interviewer. Data collection began August 28, 1995, and ended December 8, 1995. The data were collected by the survey contractor’s field staff. This staff consisted of 149 interviewers under the supervision of seven regional supervisors and their assistants and a central office staff consisting of a project manager, a field director, and a subsampling assistant. Interviewers: Prior to beginning the interview, the interviewer observed the outside of the building to ascertain if the structure met the size and building-use eligibility requirements of the survey. If the building failed to meet any one of the definitional criteria, the building was classified as ineligible and no interview was conducted. During the initial visit to the sampled buildings, the interviewers identified and attempted to schedule an interview with a knowledgeable respondent who met the survey criteria for a building representative. The respondent could be the owner of the building, a tenant, a hired building manager or engineer, or a spokesperson for a management company. The Interview: Each interview began with a series of screening questions designed to verify the building’s address and eligibility for the survey. Respondents were asked about the building as a whole rather than individual establishments located within the building. The completed building interview lasted an average of 40 minutes. That included the time for the interviewer to record the results of the screening, to ask all questions on the building characteristics questionnaire, and to obtain a signed authorization form from the respondent for the release of energy billing data from the energy supplier to the building. It did not include the observation time prior to the interview to determine if the building was eligible or the time needed to obtain a signed authorization form from someone other than the building respondent in those cases when the building respondent did not have the authority to sign the form. The average time to obtain each completed interview, including interviewer preparation, travel, callbacks, interviewing, and transmitting the completed interviews to the home office, was 6 hours and 54 minutes. Each interviewer conducted an average of 53 interviews: 5 interviewers each completed 10 or fewer interviews, while 6 interviewer each completed more than 70. Interviewer Supervision: Procedures were taken to ensure that the interviews were conducted as intended. Ten percent of each interviewer’s cases were preselected for validation to verify that the interview had been conducted and that it had been conducted at the correct building according to specified procedures. That validation occurred by telephone at the survey contractor’s home office. If a disproportionate percentage of an interviewer’s validation cases were classified as ineligibles or nonrespondents, additional cases were selected as needed to ensure 10 percent coverage of responding cases for each interviewer. Interviewers were informed that a sample of their work would be validated, but they were not informed which completed interviews would be checked. If a field supervisor was concerned about a particular interviewer, he or she conducted discretionary validations. Minimizing Nonresponse Several approaches were employed in an effort to minimize nonresponse, including: advance mailings to building owners or managers; in-person visits; telephone callbacks; establishment of a toll-free “hot-line” number to address respondents’ concerns or questions; personalized letters to documented refusals; and provision of additional field staff in several Metropolitan Statistical Areas to help those who still had problem cases. These approaches dealt with the three categories of nonresponse for CBECS: (1) refusals, (2) cases where the knowledgeable respondent was located outside of the sample PSU’s, and (3) cases where the respondent was unavailable during the field data collection period. An additional type of nonresponse conversion dealt with respondents who declined to sign the authorization forms that would allow their energy suppliers to release the building’s energy consumption records and information on demand-side management program participation. Personalized written requests for signed authorization forms were mailed for all buildings for which energy usage had been reported and a signed form had not been obtained by an interviewer. Such requests were mailed to 219 buildings interviewed by field staff. A total of 24 signed authorization forms were received by mail. Processing the Data The initial processing of the CBECS data occurred at the survey contractor’s home office and included receipt of the CBECS questionnaires as they were transmitted from the field, editing the questionnaires, calculating the survey weights for each building, and masking the data for confidentiality before it was transmitted to EIA. Final data preparation occurred at EIA and consisted of checking the data for internal consistency, checking the data against data from previous surveys, conducting imputation procedures for missing data, and preparing cross-tabulations for release to the public. Data Editing: Data editing for the 1995 CBECS Building Characteristics Survey occurred at several points during data collection and processing. Initial editing occurred during the Computer-Assisted Personal Interviewing (CAPI) interview. Additional editing occurred upon receipt of the questionnaire for data processing and during data entry. The final data editing occurred during review of data frequencies and cross-tabulations. CAPI Edits During Interview: Data collection using CAPI techniques allowed for some data editing to occur during the interview, thus ensuring higher quality of data, as well as reducing the time required for post-interview editing. Higher quality of data was achieved by programming skip patterns that prohibited the entry of ineligible codes directly into the CAPI questionnaire. Data Editing at Home Office: Completed questionnaires were transmitted electronically to the survey contractor’s home office and the hard-copy materials were mailed. Clerks reviewed the hard-copy materials to locate a signed authorization form and any hard-copy listings of account numbers and supplier customer lists used to supplement CAPI. Linkage of the building with the energy supplier was completed as part of the processing of building survey data. Edits at this stage were of three types: (1) missing data checks, (2) automated logic checks that verified compliance with codes and skip patterns as specified in the codebook, and (3) inter-item consistency checks. The survey contractor took several steps to resolve inconsistencies or ambiguities in the data. First, the contractor reviewed other parts of the questionnaire for explanations that might help solve the problem. Several open-ended questions were included in the questionnaire that allowed the respondent to either describe or include additional information about a particular item. Also, the interviewers had been asked to write comments in “comment boxes” to explain unusual circumstances. These open-ended questions and notes were relied upon extensively in the resolution process and were very helpful in explaining some of the inconsistencies. Second, in some hard-to-resolve cases, EIA personnel provided technical guidance on how to reconcile some questionnaire responses. Finally, when these efforts failed to resolve a problem, especially when the energy sources or heating and cooling equipment were involved, the survey contractor contacted the respondent by telephone for clarification. Overall, telephone contacts to clarify both questionable or missing information were completed for the respondents of 602 buildings, 10 percent of all completed cases. All changes made to any questionnaire response as a result of these reviews were carefully documented and explained on an error-resolution sheet attached to the questionnaire. As the last step prior to the delivery of the draft data tape to EIA, the contractor produced data frequencies and cross-tabulations. These were reviewed to reveal any outlying values and inconsistencies that the edits may not have identified. Inconsistencies were corrected by the contractor before data tapes were transmitted to EIA. Top Continue to “Energy Suppliers Survey” Specific questions on these topics may be directed to: Joelle Michaels joelle.michaels@eia.doe.gov CBECS Manager Phone: (202) 586-8952 FAX: (202) 586-0018 URL: http://www.eia.doe.gov/cbecs/tech_survey_building.html |