Appendix A.  Cautions when Using Data



Occasionally, data are subject to misinterpretation and misuse.
When reviewing the RTECS data, the following items should be kept
in mind in order to avoid this misuse.

     1.   This is the first time that all RECS data have been made
          available for all RTECS sampled households.  When
          tabulating RECS household variables, using the RTECS
          public use diskettes, differences from the published RECS
          tabulations will occur because the RTECS households are
          a subsample of the RECS households.  Anyone whose real
          interest is the RECS household data, should use the 1990
          RECS Public Use Data Files.  See the "Note:" on the
          following page for ordering information.

     2.   The results published in the reports and any weighted
          estimates generated from this file are based on a sample
          survey--not every unit in the population was included in
          the survey.  This means that there is some variability in
          the estimates because the sample that happened to be
          chosen for the survey is only one of many samples of
          households that could have been selected.

          An estimate of this variability is provided for each
          estimate in the published report through the Row and
          Column factors. 

          The RTECS sample design is not a simple random sample. 
          When estimating the variance of a statistic, a researcher
          can not use equations that are based upon the assumption
          that the sample is a simple random sample.


     3.   Be careful in trying to informally derive estimates for
          data that are suppressed from the tables.  Data are
          suppressed because these data cannot be reliably inferred
          from other available data.

          Data in the report were suppressed when the relative
          standard error (RSE) for the estimate exceeded 50
          percent.  See the published reports for a discussion on
          relative standard errors.

          In addition, for tables showing household counts, we did
          not publish estimates that were based upon fewer than 10
          sample cases because such estimates tend to be un relia-
          ble, even if the estimated RSE was less than 50 percent.
          For tables showing vehicle counts, we did not publish
          estimates that were based on fewer than 18 vehicles (1.8
          vehicles per household).
     4.   When counting the number of RTECS households, the sum of
          the weights (WEIGHTJ) should be used.  To determine
          households possessing vehicles, use the filter VSMAX not
          equal to '00'.

     5.   General coding rules are 1 = YES and 0 = NO.
These are the cautions that were included with the RECS Public Use
Data.  They should be kept in mind when using RECS variables.

     1.   BTUNG is coded as '9999999' and DOLLARNG is coded as
          '99999' if the household does not use natural gas. 
          Similarly, BTUELSPH is coded as '9999999' and DOLELSPH is
          coded as '99999' if the household does not use
          electricity for space heating even if the household uses
          electricity for other uses.  The same holds for all fuels
          and all end uses.

     2.   If natural gas is used as a secondary space-heating fuel,
          then BTUNGSPH is not '9999999'.  Hence, there are some
          households where part of the natural gas consumption is
          assigned to space heating yet the household does not use
          natural gas as the main space-heating fuel.  The same
          holds for water heating and for all fuels.  In
          particular, the majority of kerosene is consumed for
          space heating in households where kerosene is not the
          main space-heating fuel.

          Households using an energy source for main space heat are
          not coded to use it as a secondary source.  Therefore, as
          an example, a household could use electricity as the
          source of their main space heat, and also use electricity
          in a space heater, but the energy source is not coded as
          secondary.

     3.   The area sample listings were updated in the spring and
          early summer of 1990.  Most interviews were conducted in
          the fall of 1990.  Hence the 1990 RECS does not represent
          the total population of housing units built in 1990.

     4.   General coding rules are 1 = YES and 0 = NO.  There are
          two exceptions to that rule:
          AUXEQUIP = 0 for YES and 1 for NO.
          AUXFUEL = 0 for YES and 1 for NO.

     5.   The variable BTUELCOL can include electricity consumption
          for both room and central air conditioning if both are
          present in the home.

     6.   The variables depicting energy consumption in BTU are in
          thousands of BTU.

     7.   Although fuel oil may not have been purchased, there are
          a few cases where the tank had fuel oil and fuel oil was
          used during the heating season.

     8.   The 30-Year Average for Heating Degree-Days and Cooling
          Degree-Days is based on the years 1951-1980 and not
          1961-1990.

     9.   Heated floorspace is measured (variable is HEATED). 
          Cooled floorspace is estimated using the ratio of number
          of rooms usually cooled (RMSCOOL) to the number of total 
          rooms (BEDROOMS + OTHROOMS) multiplied by the total
          floorspace in the home (HOMEAREA). 

     10.  The appliance component in the past included
          refrigerators.  In 1990, end-use consumption for
          refrigerators is a separate estimate (BTUELRFG).
          Therefore, 1987 does not contain BTUELRFG and the
          BTUELAPL is not the same in 1987 as in 1990.

     11.  Although the end-use consumption estimate for freezers is
          on the data file (BTUELFZZ), it also is part of the
          appliance component (BTUELAPL).

     12.  When comparing consumption data to data from other
          sources, be sure to examine the potential effects of
          differences in the way the data sources are
          produced--differences in target population, concepts
          being measured, questionnaire wording, survey
          administration method, and other sources of nonsampling
          error described in Appendix B of the Household Energy
          Consumption and Expenditure 1990 report.

          A discussion of the differences between the estimates in
          this report and other Energy Information Administration
          estimates of energy used in the residential sector is
          provided in Appendix C of the Household Energy
          Consumption and Expenditure 1990 report.

     13.  When comparing 1990 data with 1987 data, there are
          several areas in which caution should be taken.  See
          item 10 above.  Weather differences between the two
          survey periods may also  account for differences that
          are observed in the estimates.

     14.  It is important to review Appendix B, "Quality of
          Specific Data Items", starting on page 147 of the
          Household Energy Consumption and Expenditure 1990 report
          or page 210 of the Housing Characteristics 1990 report
          before undertaking analysis using RECS data.  

     15.  When counting the number of RECS households, the sum of
          the weights (NWEIGHT) should be used.  Note: NWEIGHT is
          not on the RTECS Public Use Diskettes.  WEIGHTJ is used
          in RTECS.  These weights are different. 

     16.  The Btu conversion factors used for this survey were:

          Electricity     3,412 Btu/kilowatthour
          Natural Gas     1,027 Btu/cubic foot *
          Fuel Oil No. 1  135,000 Btu/gallon
          Kerosene        135,000 Btu/gallon
          Fuel Oil No. 2  138,690 Btu/gallon
          LPG (propane)    91,330 Btu/gallon
          Wood            20,000,000 Million Btu/cord 

          *  Unlike previous RECS where a standard conversion
          factor was used for converting between cubic feet and Btu
          of natural gas, the conversion rate varied by company for
          the 1990 RECS.  The 1,027 Btu/cubic foot conversion rate
          was an average of those reported on Form EIA-176, "Annual
          Report of Natural and Supplemental Gas Supply and
          Disposition."  See "Confidentiality Provisions" as to why
          calculations based on cubic feet may differ from the
          published results.




          Questions regarding these and other methodological issues
          can be directed to Ron Lambrecht, Survey Manager, at
          (202) 586-4962.


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