|Energy Information Administration Residential Transportation Energy Consumption Survey Channel.  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                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  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        Home Page > **How the Survey Was Conducted**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
|**Appendix A**
**How the Survey Was Conducted**


**Introduction**


      The Residential Transportation Energy 
        Consumption Survey (RTECS) was designed by the Energy Information Administration 
        (EIA) to provide data about vehicles that are used for personal transportation 
        in the United States. These data include the motor vehicle stock, the 
        vehicle-miles traveled (VMT), and the vehicle fuel consumption and expenditures. 
        The RTECS is a companion survey to the Residential Energy Consumption 
        Survey (RECS), which collects household energy consumption and expenditure 
        data. The RTECS collects vehicle information through personal interviews, 
        telephone interviews, and mail questionnaires with a representative national 
        sample of households. Copies of the data collection forms are provided 
        in Appendix D, "Survey Forms." The 1994 RTECS is the fifth such 
        survey covering a calendar year conducted by EIA; previous surveys were 
        collected in 1983, 1985,1988 and 1991. Prior to the 1983 RTECS, monthly 
        surveys were conducted from June 1979 to September 1981. Beginning with 
        1985, the surveys have been conducted triennially. The 1994 RTECS was 
        the last in the series.
      This appendix provides detailed information 
        concerning: (1) the RTECS survey design, including a comparison between 
        the 1994 and previous years RTECS designs; (2) the sample design; (3) 
        the data-collection procedures; (4) the Vehicle Identification Number 
        (VIN); (5) interviewer training; (6) efforts undertaken to minimize the 
        nonresponse biases; (7) survey estimate weights; (8) data-editing procedures; 
        (9) data-preparation procedures; and (10) data confidentiality and the 
        preparation of the public-use data tape.
      **Changes 
        in Survey Design and Data Collection**
      The survey design for the 1994 RTECS was 
        unchanged from the 1988 and 1991 survey, but there were several additional 
        questions. The beginning of year data collection was combined with the 
        RECS personal interview for efficiency reasons. Fuel efficiencies continue 
        to be estimated by using the Environmental Protection Agency (EPA) laboratory-test 
        miles per gallon (MPG) adjusted for on-road fuel efficiency shortfall. 
        (See Appendix B, "Estimation Methodologies," for further discussion.) 
        Major details of the 1994 RTECS design and data collection included the 
        following:
      The sample size of the 1994 RTECS was 
        3,020 households, similar to the 1988 and 1991 RTECS which had 2,986 and 
        3,045 households respectively.
      Respondents in the 1994 RTECS were once 
        again not asked to maintain monthly fuel-purchase diaries.
      The number of contacts with respondents 
        required to collect the data in 1994 was 10 per household for the beginning-of-year 
        and end-of-year periods.
      In 1994, MPG and fuel-price data were 
        estimated in the same manner as in 1988 and 1991. MPG data were estimated 
        using adjusted test laboratory MPG as recorded on the EPA Emissions Certification 
        files. Fuel-price data were obtained from the Bureau of Labor Statistics 
        (BLS) gasoline pump price series and the Lundberg Survey, Inc., price 
        series. (See Appendix B, "Estimation Methodologies," for a detailed 
        discussion of the estimation procedures used in this report.)
      Respondents were again asked to provide 
        the VIN for each vehicle. The decoded VIN was used to enhance the accuracy 
        of reported vehicle characteristics. These characteristics were used to 
        match sampled vehicles to the EPA Certification files. (See "The 
        Vehicle Identification Number" section in this appendix for a detailed 
        discussion of the VIN). Households in the 1994 RTECS did not receive a 
        monetary incentive to participate.
      **Sample Design**
      The sample design for the 1994 RTECS consisted 
        of a self-weighting national sample of households . As of July 1994, the 
        target population for the RTECS was estimated at 97.3 million households, 
        based on adjusted estimates of households from the U.S. Bureau of the 
        Census, *Current Population Survey* (CPS). The universe for the 
        RTECS is comprised of all housing units occupied as the primary residence 
        in the 50 States and the District of Columbia. (See "Glossary" 
        for a definition of Housing Unit.) The sample of households selected for 
        the 1994 RTECS was based on the 1993 RECS multistage area probability 
        sample. The RECS incorporates a rotating panel that allows the observation 
        of changes in energy use over time when the same households are in two 
        successive surveys. The original RECS sample consisted of 8,753 units, 
        of which 1,642 were not completed. (See *Housing Characteristics 1993* 
        (published June 1995), DOE/EIA-0314(93), for a detailed discussion of 
        the RECS Sample Design.)
      The RTECS sample consisted of 3,020 housing 
        units selected from the 7.011 available 1993 RECS housing units for which 
        data were successfully collected.
      The fraction of RECS housing units selected 
        for RTECS was 59.8 percent. At the beginning of the data collection period 
        in October 1993, 2,842 (93.3 percent) of the 3,020 housing units were 
        identified as housing units that could potentially be contacted by telephone, 
        and 200 housing units (6.6 percent) were identified as households that 
        could not be contacted by telephone, either because they did not have 
        telephones, had unlisted numbers, or refused to provide a telephone number 
        during the RECS interview. This group was classified as mail households 
        and data were collected from these households via a mailed questionnaire 
        rather than a telephone interview. Contact was not attempted for an additional 
        3 households. By the end of the RTECS survey cycle (March 1995), the percent 
        of households considered mail households had increased to 485, or 16 percent, 
        because of an increased number of households with unlisted numbers or 
        disconnected telephones.
      **Data Collection**
      The RTECS was divided into three data 
        collection phases. The first beginning of year data collection was combined 
        with the RECS personal interview. During this interview, the household's 
        vehicle stock was enumerated, and the VIN and the odometer reading for 
        each vehicle were recorded. Household characteristics were also collected. 
        Phases two and three: Mid-Year (M-Y) data-collection, and End-of-Year 
        (E-O-Y) data collection, were conducted via telephone interviews. For 
        households that could not be contacted by telephone, the data were collected 
        via a mail questionnaire.
      **M-Y 
        Data-Collection Phase:**The M-Y mailing consisted 
        of a letter from the Director of the Office of Energy Markets and End 
        Use and a vehicle update worksheet for the respondents to complete. At 
        this time, no vehicle characteristic data were obtained; only an inventory 
        update was collected. The respondent was instructed to either keep the 
        worksheet by the telephone for the telephone interview or return the worksheet 
        by mail, if the household was classified as a no-telephone household. 
        Any respondent who had refused at the B-O-Y interview was not contacted 
        during the M-Y data collection phase. These households were not contacted 
        at the M-Y interview, in order to increase the probability that the household 
        would respond to the E-O-Y data collection. During the telephone interview, 
        data were collected using the RTECS questionnaires.
      One week prior to each M-Y and E-O-Y data 
        collection, a mailing was sent to the RTECS respondents. The E-O-Y mailings 
        consisted of the following: (1) Odometer Reading Cards; (2) VIN cards; 
        (3) a page of instructions; (4) a letter from the Director of the Office 
        of Energy Markets and End Use of the EIA explaining the survey; and (5) 
        a letter from the survey contractor explaining their role in the survey.
      **E-O-Y 
        Data-Collection Phase:** Data collected during the E-O-Y 
        phase consisted of an update of the vehicle stock and the following vehicle 
        characteristics for each vehicle recorded: the make, model and model year, 
        engine size, fuel system type, and transmission type; vehicle fuel characteristics 
        such as the fuel type, fuel grade and type of pump service; odometer readings; 
        and VIN. See below for description of M-Y data collection.
      **Data Collection 
        Dates**
      The B-O-Y data collection occurred during 
        the end of October 1993 through early February 1994. The M-Y update occurred 
        in July and August 1994, and the E-O-Y data collection took place during 
        January, February and March of 1995.
      **Data-Collection 
        Instruments**
      The data-collection instruments for the 
        RTECS consisted of four types: (1) the 1993 RECS questionnaire, (2) Odometer 
        Reading Card, (3) Vehicle Identification Number Card, and (4) RTECS questionnaires. 
        (See Appendix D, "Survey Forms," for examples of these data 
        collection instruments.)
      **1993 Residential Energy Consumption 
        Survey Questionnaire (Form EIA-457A)**--This form was used during 
        the RECS personal interview. Questions on this form included the number 
        of vehicles in the household, and for each vehicle: the VIN; the vehicle 
        type; the vehicle make, model, and model year; the odometer reading; and 
        estimated miles traveled during the past year or since the vehicle was 
        acquired, if the vehicle was acquired within the previous 12 months. Household 
        characteristics questions included the number of household members, and 
        for each household member: their age, gender, employment status, and relationship 
        to the head of household. The education level and ethnic background were 
        collected for the head of the household only. The number of drivers, annual 
        family income, and income assistance were collected for the household.
      **Odometer Reading Card (Form EIA-876A,D)**--This 
        form used by the RECS data collector during the combined RECS/RTECS data 
        collection and was mailed to the respondent prior to the E-O-Y data collection 
        and was used as a reference by the respondent during the telephone interview. 
        The card was used to record, on an assigned date, the odometer readings 
        for each reported vehicle during both the B-O-Y and E-O-Y data collections. 
        A computer-generated label attached to the card identified each vehicle 
        by make, model, and year of the vehicle. The respondents were instructed 
        to enter the vehicle's odometer reading on the card after the last use 
        of the vehicle on the specified assigned date. For the B-O-Y data collection, 
        the date of the RECS data collection was used if the vehicle was available. 
        If the vehicle was not available, the card was left with the respondent 
        to be filed out and dated when the vehicle was recorded. For the E-O-Y 
        data collection, cards were mailed to respondants to be filled out.. No 
        odometer reading cards were provided during the M-Y data collection. An 
        additional odometer reading card without a computer-generated label was 
        included for the respondent to record odometer readings for any vehicle 
        acquired since the last contact.
      **VIN Card (Form EIA-876)**--This 
        form was mailed to the respondent and used as a reference during the telephone 
        interview. The card was used to record the VIN for each reported vehicle. 
        Each VIN card had a computer-generated label identifying the specific 
        vehicle assigned to the card. A thorough explanation of the VIN and where 
        to locate it was provided on the card. A blank VIN card was also provided 
        to record the VIN for any vehicle acquired since the last contact. For 
        the E-O-Y data collection, the VIN was collected only from households 
        that had acquired a new vehicle at the M-Y data collection phase. Households 
        were not mailed a VIN card if they had refused to provide a VIN at the 
        time of the RECS contact, or if they were previously classified as a nonrespondent 
        household.
      The odometer and VIN cards were mailed 
        to the respondents approximately 1 week prior to the telephone interview. 
        The respondents were requested to keep both the odometer and VIN cards 
        by their telephones so they would be readily available when the interviewer 
        telephoned. If the household was classified as a no-telephone household, 
        the respondent was requested to return the cards in a self-stamped, business 
        reply envelope that was provided.
      **Residential Transportation Energy 
        Consumption Survey Questionnaire (Form EIA-876B,A)**--This form 
        was used by the telephone interviewer to record information gathered during 
        the telephone interviews. Vehicle data obtained with this questionnaire 
        included: verification of the stock of vehicles; motor vehicle characteristics 
        for each vehicle, such as transmission type, drive type, fuel system type, 
        engine size, and number of cylinders; vehicle fuel characteristics such 
        as fuel type, fuel grade and type of pump service; odometer readings; 
        and VIN. The questionnaire consisted of two types: the M-Y mail and telephone 
        questionnaire (Form EIA-876B), and the E-O-Y telephone questionnaire (Form 
        EIA-876A).
      The B-O-Y and E-O-Y telephone questionnaires 
        were used only by the telephone interviewers to record respondents answers 
        during the telephone interview.Thesequestionnairesweredividedinto discrete 
        sections that were color-coded to help the interviewer in determining 
        the correct skip patterns.
      **M-Y 
        Questionnaire:**The M-Y Questionnaire that was mailed to the respondents requested 
        only minimal vehicle update information on the acquisition and disposition 
        of vehicles since the B-O-Y data collection. Respondents with telephones 
        were requested to complete the form and to keep it by the telephone in 
        preparation for the telephone interview. The respondents without telephones 
        were requested to complete and return the form to the survey contractor. 
        The M-Y questionnaire used by the telephone interviewers to record the 
        respondents answers contained:
      A call record sheet and protocol
      Computer-generated pages showing the most 
        recent vehicle inventory for the household
      Questions relating to the vehicles disposed 
        of since the RECS interview
      Questions relating to the vehicles acquired 
        since the RECS interview
      Questions pertaining to the household's 
        intention to move within the following 6 months.
      Note: For a selected number of households, 
        additional questions pertaining to government assistance to low-income 
        households and interruptions in home heating were asked at the end of 
        the RTECS interviews. These data, collected as part of the Family Support 
        Administration (FSA) update to RECS, were completely independent from 
        the RTECS questions. The FSA questions were collected during the RTECS 
        data collection as a cost-saving measure and as a method of reducing the 
        respondent burden by combining the two telephone contacts into one telephone 
        call.
      **E-O-Y 
        Questionnaire:**Two types of questionnaires were used for the E-O-Y data collection, 
        depending on the responses at the M-Y interview. For households that had 
        indicated at the M-Y update that they had acquired or disposed of a vehicle, 
        the questionnaire contained two additional sections. The first new section 
        pertained to acquired vehicles and contained questions about the vehicle 
        characteristics, the VIN, and the odometer reading. The second section 
        pertained to disposed vehicles. An additional computer printout was included 
        listing the new vehicles obtained at the M-Y. For households that did 
        not indicate at the M-Y update that they had acquired or disposed of a 
        vehicle, the questionnaire was similar to the B-O-Y questionnaire, including 
        questions pertaining to vehicle acquisitions and disposals since the last 
        contact. A section on other transportation modes was also added. Questions 
        relating to the household's intention to move were eliminated.
      **Vehicle Identification 
        Number**
      In the 1994 survey, respondents were again 
        asked to provide the VINs for their vehicles. The VIN is a unique identification 
        number assigned to a vehicle by the automobile manufacturers for the purpose 
        of identification.
      Beginning with the 1981 vehicle model 
        year, the U.S. Department of Transportation (DOT) has required that a 
        standard identification format consisting of 17 characters be attached 
        to all over-the-road vehicles sold in the United States. Between 1954 
        and the 1981 DOT standard, automobile manufacturers in the United States 
        had included an 11- to 15-digit VIN on all vehicles.
      In the 1991 RTECS, the MPG data were estimated 
        using EPA laboratory test results of MPG (See Appendix B, "Estimation 
        Methodologies," for a complete discussion of the consumption and 
        expenditure estimation procedures used in the 1994 RTECS.) To assign a 
        test MPG to a particular vehicle, the specific characteristics of the 
        vehicle were required. In the 1994 RTECS, these vehicle characteristics 
        were obtained from two sources: (1) the decoded VIN's, and (2) the RTECS 
        questions about vehicle characteristics that the respondent answered. 
        The 1994 RTECS also provided a unique opportunity to assess the reliability 
        of the respondents' answers by comparing their responses to the RTECS 
        vehicle characteristic questions with an independent source of data containing 
        the vehicle characteristics for the same vehicles, that is, the VIN.
      **The Decoded 
        VIN**
      The VIN is a sequence of numbers and letters 
        that, when decoded, provides vehicle characteristics that range from the 
        nation of origin to the individual assembly plant where the vehicle was 
        manufactured. The first three characters of the standard VIN format, designated 
        as the World Manufactures Identification (WMI), identify the nation of 
        origin, the manufacturer, and the vehicle make. The next five characters 
        are the Vehicle Description Section (VDS). These characters identify the 
        vehicle model; the body type such as sedan or station wagon; the engine 
        type, which includes characteristics like the number of cylinders, cubic 
        inch displacement and net brake horsepower; the restraint system found 
        in the vehicle; and a model change code. There is no fixed format or standard 
        codes within this five-character field. The ninth field contains a check 
        digit. The check digit is an internally consistent number computed from 
        the other identification numbers according to a mathematical formula. 
        It is used during the decoding process to verify the accuracy of the other 
        identification numbers. The next section is the Vehicle Identification 
        Section (VIS) and contains eight characters. The first character in this 
        section is the vehicle model year, the second character is the assembly 
        plant name and/or location. The last six letters in this final section 
        represent the sequential production number for a specific vehicle. To 
        protect the confidentiality of the respondents, the sequential production 
        number for a specific vehicle was not included on the RTECS public-use 
        tape.
      **Location of 
        the VIN**
      In most passenger cars the VIN is attached 
        to the left side of the dash or instrument panel and is visible through 
        the outside of the windshield. In some instances, the VIN is located on 
        the inside of the door panel on the driver's side. Imported automobiles 
        often attach the VIN to the windshield pillar post or on top of the steering 
        column. Also, the VIN can be inscribed on the following documents: insurance 
        cards, vehicle registrations, vehicle titles, safety or emission certificates, 
        insurance policies, and bills of sale.
      **Collecting 
        the VIN**
      The initial collection of the VIN occurred 
        during the RECS. Since the RECS data are collected in personal interviews, 
        this survey would allow the interviewer to actually record the VIN from 
        either the vehicle or a document.
      The survey design allowed for the collection 
        of the VIN during several different stages of the RTECS, thus eliminating 
        the need to rely on a one-time effort. The VIN could be obtained during 
        the RECS interview or during the E-O-Y interview. Only the RTECS households 
        that did not provide a VIN at the time of the RECS interview, or for which 
        the VIN was incorrectly transcribed during the RECS, were asked to provide 
        the VIN again during the RTECS E-O-Y data collection. A household that 
        had refused to provide a VIN at any time was not asked for the VIN a second 
        time. RTECS precollection mailings to the households contained an explanation 
        of the VIN and how to locate and record it.
      The importance of obtaining an accurate 
        VIN for a successful RTECS was emphasized during both the RECS and RTECS 
        interviewer training sessions. Considerable interviewer training time 
        was allocated to describing the VIN and providing the interviewers with 
        thorough directions for locating and recording the VIN.
      **The Interview**
      The primary method of data collection 
        for the 1994 RTECS was a the combined RECS and RTECS personal interview. 
        (For the 6.5 percent of the RTECS households that could not be contacted 
        by telephone, the VIN Cards, Odometer Reading Cards, and a postage-paid 
        return envelope were mailed along with instructions directing the respondents 
        to return the cards in the envelopes.) The M-Y interview lasted approximately 
        5 minutes. The average E-O-Y telephone interviews lasted 12 minutes. Most 
        respondents had recorded the odometer readings and VIN for each vehicle 
        on the cards they received prior to the telephone calls.
      The initial vehicle data were collected 
        in the RECS personal interview. This interview lasted an average of 62 
        minutes. However, motor vehicle data were only one type of energy data 
        collected at this time and were a small part of the respondent burden. 
        Information about the structural features of the housing unit, the heating 
        and cooling systems, energy fuel used, and conservation improvements were 
        among the nonvehicle type of energy data collected.
      **Interviewers 
        and Interview Training**
      All interviewers attended a three day 
        training course prior to the RECS/RTECS data collection and a 3-hour training 
        sessions held just prior to the E-O-Y data collection anda75-minutetrainingsessionpriortotheM-Y 
        data collection. Interviewer trainers were staff members from the survey 
        contractor who were familiar with the RECS and RTECS. The RECS/RTECS training 
        sessions were observed by the EIA RTECS Survey Manager. See the *Housing 
        Characteristics 1993*for additional**information.
      For the telephone portion, all interviewers 
        were provided with a booklet of instructions. The first half of the training 
        sessions consisted of general instructions pertaining to the RTECS forms, 
        with a thorough explanation of the VIN and a discussion of possible trouble 
        areas. During the second half of the training session, the interviewers 
        were divided into three small groups. Three mock interviews were completed 
        in each of these groups.
      Immediately following each training session, 
        the interviewers began contacting respondents. All telephone interviews 
        were initially monitored by contractor supervisory personnel who were 
        then able to provide instant feedback to the interviewer. Subsequent periodic 
        monitoring occurred during each data-collection phase.
      **Minimizing 
        Nonresponse Bias**
      Nonresponse bias is one type of nonsampling 
        error that contributes to the total error of a survey. Other nonsampling 
        errors include population undercoverage during sampling, interviewer error, 
        coding and/or key punching errors, and response bias. The wording and 
        format of the survey questionnaires, the procedures used to select and 
        train interviewers, and the quality-control procedures built into the 
        data collection and processing operations were all designed to minimize 
        these sources of error (See Appendix C, "Quality of the Data," 
        for a discussion of nonsampling errors other than nonresponse bias.)
      It was recognized in the early planning 
        stages of the 1994 RTECS that special attention would have to be given 
        to minimizing nonresponse bias, since the RTECS households were contacted 
        several times a year, in addition to the initial RECS personal interview. 
        The following steps were taken to minimize the nonresponse:
      If possible, the VIN was collected during 
        the RECS interview, thus, reducing the need to ask for the VIN during 
        the RTECS, if it was successfully collected during the RECS
      The M-Y data collection instrument was 
        streamlined with the primary emphasis placed on updating the vehicle stock 
        and obtaining the odometer readings for any disposed of or acquired vehicle. 
        The vehicle characteristics and VIN for newly acquired vehicles were collected 
        during the E-O-Y data collection instead of during the M-Y update
      No M-Y data collection was attempted for 
        households declared as legitimate refusals at the initial interview. All 
        households were recontacted for the E-O-Y data collection; however, only 
        households that previously had a valid odometer reading were asked to 
        provide the E-O-Y odometer reading. None of the households that previously 
        refused were asked any VIN questions
      A letter describing the survey and its 
        importance was mailed to the households approximately one week prior to 
        the B-O-Y and E-O-Y telephone interviews
      The interviewers were requested to attempt 
        a minimum of eight telephone calls before the household was classified 
        as a noncontact and in many cases made up to 16 or more attempts to contact 
        the household. (See *Housing Characteristics 1993*, DOE/EIA-0314(93), 
        for a detailed discussion of the efforts to minimize nonresponse bias 
        in the RECS.)
      **Imputations**
      In the instances when a RECS respondent 
        refused to participate in one or more of the RTECS data collection phases, 
        a decision was made to impute the missing data rather than readjust the 
        weights to account for the RTECS nonresponse because of the availability 
        of RECS data for these households. Missing data items were imputed using 
        the following: RECS data files on vehicle characteristics; decoded VIN; 
        hot- and cold-deck procedures; linear and logistic regression; predictive 
        mean matching; and EPA data files. (See Appendix C, "Quality of the 
        Data," for a discussion of the imputation procedures used.)
      **Survey Estimate 
        Weights**
      All the statistics published in this report 
        are estimates of population values, such as the total number of households 
        in the United States. These estimates are based on a subset of the entire 
        population of households chosen according to multistage probability sample 
        selection rules. The universe includes all households in the 50 States 
        and the District of Columbia, including households on military installations. 
        Survey estimates inflate the RTECS sample results to represent the target 
        population. This required the development of weights for each sample household 
        using a multistage weighting procedure. The weights for the RTECS were 
        developed from the weights that originally had been used in the 1993 RECS. 
        These original weights were divided by the probability that a RECS household 
        was selected into the RTECS sample. The probability that an individual 
        1993 RECS household was selected for the 1994 RTECS varied by the Secondary 
        Sampling Unit (SSU) and the estimated vehicle annual mileage for the household 
        as obtained from the RECS interview.
      These RECS weights were appropriate for 
        estimates of U.S. households as of November 1993 (the midpoint of the 
        RECS data-collection time period). Since the midpoint of the RTECS data-collection 
        period was July 1994, the RTECS weights were adjusted so that RTECS household 
        counts were estimated at their presumed July 1994 levels. This was accomplished 
        by use of poststratification. In poststratification, the survey weights 
        in RTECS (and RECS) were adjusted by factors so that, within certain population 
        subgroups, RTECS estimates of household counts would agree with those 
        estimated from the CPS. Within each population subgroup or poststratification 
        cell, the weight adjustment factor was computed as the CPS household count 
        estimate divided by the RTECS household count estimate. (RTECS household 
        count estimates are produced by summing RTECS survey weights.) The CPS 
        estimates within the subgroups are called "control totals," 
        and they are considered to be more reliable than the corresponding estimates 
        from RTECS.
      The poststratification cells were defined 
        by a two-way contingency table. One margin represented metropolitan status 
        within the Census regions. This margin had 12 categories comprised of 
        4 Census regions (Northeast, Midwest, South, and West) and 3 metropolitan 
        statuses (metropolitan in center city, metropolitan outside of center 
        city, and nonmetropolitan). The other margin of the poststratification 
        table contained three categories (one-person-male households, one-person-female 
        households, and all other households). Thus, the poststratification table 
        had a total of 36 cells. However, 36 separate weight-adjustment factors 
        were not computed. Rather, the RTECS weights within these cells were adjusted 
        by a limited "raking" procedure. The weights were first adjusted 
        to agree with CPS totals for the Census region by metropolitan status 
        margin, using 12 cells. Next the weights were adjusted to CPS totals for 
        the household type margin using 3 cells. Finally, the weights were readjusted 
        to CPS totals for the Census region by metropolitan status margin. Raking 
        allows for the use of more sample units in computing each weight-adjustment 
        factor, by not distributing them around too many cells. However, the method 
        is based on the assumption that there is no significant interaction between 
        the margins of the poststratification table.
      **Data-Editing 
        Procedures**
      The following steps were undertaken to 
        ensure the accuracy of the data. Step one in the review process was to 
        verify the accuracy of the basic identifying information. Step two consisted 
        of manually reviewing the questionnaire for completeness and logical consistency 
        of selected patterns of response and to prepare the questionnaires for 
        translation into machine-readable form. In the third step, the data were 
        keyed into machine-readable format. Any inconsistencies in the skip patterns 
        were automatically noted and resolved by one of the editors. In the fourth 
        step, the keypunching of all data was verified. During the fifth step, 
        the data were machine edited to further ensure completeness, logical consistency, 
        and the legitimacy of coded values.
      Comparisons were made of the vehicle characteristics 
        provided by the respondent and the vehicle characteristics obtained from 
        the VIN. When a discrepancy occurred the vehicle characteristics obtained 
        from the VIN were usually used.
      **Report Preparation 
        Procedures**
      Prior to a final data tape, a preliminary 
        data tape was delivered to the EIA in July 1995. EIA data analysts reviewed 
        and processed the data to prepare it for the final data tape. Crosstabulations 
        were run, checked for internal consistency, and compared with data from 
        previous RTECS. Generally, inconsistencies were resolved by the survey 
        contractor. As a quality control measure, selected tabulations were produced 
        using two different software programs, Table Producing Language (TPL) 
        and Statistical Analysis System (SAS).
      A final clean edited data tape of household 
        vehicle survey data was delivered to the EIA in September of 1992. After 
        the edited data tape was provided by the survey contractor, EIA data analysts 
        further reviewed and processed the data to prepare it for release in the 
        statistical reports. Statistical tables of aggregated data were produced 
        and analyzed. The report text is based on these tables.
      **Confidentiality 
        of Information and Public-Use Tape Preparation**The EIA does not receive or take possession 
        of the names or addresses of individual RTECS respondents or any other 
        individually identifiable energy data that could be linked with information 
        describing the household. All such identifiable information is maintained 
        by the survey contractor.
      Following the publication of the statistical 
        report for the RTECS and the statistical reports for the RECS, a final 
        data file is prepared for release to the public. This tape contains both 
        the housing characteristics and energy supplier data for the RECS and 
        the vehicle data for the RTECS. Additional measures such as the stripping 
        of all geographic identifiers except Census region and Census division, 
        are taken at this time to further mask the data and to ensure that the 
        identity of the individual respondent is kept confidential.
      File Last Modified: 14 August 1997
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