million Btu's (101.5 million plus or minus three million) from an estimate based on a complete census.

Similarly, the index of electricity consumption for single family households is 109 (all households = 100). The standard error for this index is approximately three index points.

All survey results are also subject to errors of response and nonreporting. In particular, errors of response may have large effects on survey responses that are based on memory (e.g., trips taken in past twelve months). Errors due to nonreporting may have occurred at various points in the development of estimates of household energy consumption (e.g., interview not completed, authorization to obtain information from utility companies not signed, information not obtained from utility company). Possible errors resulting from these nonreporting patterns are not reflected in sampling error estimates.