APPENDIX D: DESCRIPTION OF DATA
APPENDIX D 

APPENDIX D 

DESCRIPTION OF DATA

STRUCTURE OF THE DATA FILES 

BASIC STRUCTURE 

The EIA public-use data are organized into two different data files, which are available to 

users in two formats: Microsoft Excel and ASCII (comma-separated values) on 

http://www.eia.doe.gov/emeu/rtecs/nhts_survey/2001/index.html#pubuse. Table D1 illustrates the 

structure of the two files, with a description of which data are included in each file, the record 

level, and the variables that are needed to uniquely identify a record (i.e., Identifier or ID 

variable). 

For each data variable, the codebook contains: 

• a variable name, 

• a code(s) associated with the variable and code descriptions, 

• a variable label. 

Table D1. Data Files 

Data File Information 

Included 

Observation Level ID Variable National 

Sample 

Weight 

EIA 

Household 

File 

Energy-related data 

for households

One record per 

household HOUSEID EXPFLHHN 

EIA Vehicle 

File 

Energy-related data 

for vehicles 

One record per 

vehicle 

HOUSEID 

VEHID 

ID11 

(HOUSEID +

VEHID) EXPFLHHN 

RELATIONSHIP AMONG U.S. DOT AND EIA PUBLIC-USE DATA FILES 

The figure below depicts the EIA and the January 2004 release of the 2001 NHTS data, as

well as their inter-relationships. 

ENERGY INFORMATION ADMINISTRATION/HOUSEHOLD VEHICLES ENERGY USE: LATEST DATA &

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164
APPENDIX D 

Figure D1. Relationships among Data Files Released by EIA and NHTS 

EIA Household File

• Table-specific

household 

characteristics 

• Energy-related 

household variables 

• Identifier: HOUSEID 

HOUSEID 

HOUSEID 

HOUSEID 

HOUSEID + 

VEHID 

ID11 

NHTS Household File

• All household 

Characteristics 

• Identifier: HOUSEID 

EIA Vehicle File 

• Table-specific vehicle 

characteristics 

• Energy-related vehicle 

variables

• Identifiers: 

ID11(HOUSEID + 

VEHID) and 

HOUSEID 

NHTS Vehicle File

• All vehicle 

characteristics 

• Identifiers: HOUSEID 

and VEHID 

UNDERSTANDING THE DATA FILES

The purpose of this section is to present information about the EIA household and vehicle

file to data users. Based on a recommendation from U.S. DOT, only “100-percent households” 

and their light-duty vehicles are contained in EIA’s public-use files; hence, care should be taken 

when combining data from NHTS with EIA’s augmented energy and energy-related data to avoid

any misinterpretations. 

The following files are available as public-use data: 

• EIA Household File contains table-specific household characteristics and energyrelated household variables for 21,178 households. Important: To calculate results 

comparable to those found in this report, data users must exclude in their tabulations

those households that do not have light-duty vehicles. EIA has included a variable, 

HHVEHLC, for that purpose. 

• EIA Vehicle File contains table-specific vehicle characteristics and energy-related

vehicle variables for 42,736 light-duty vehicles that EIA used to calculate the number 

and type of light-duty passenger vehicles, annual mileage, type of fuel used, and 

price paid for fuel, all of which are required to measure the consumption and

expenditure associated with the nation’s residential travel. 

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APPENDIX D 

• NHTS Household File contains all the households data collected during by the 

NHTS. To identify the households in the national sample of “100-percent household”

having at least one light-duty passenger vehicle (passenger cars, vans, sport utility 

vehicles, pickup trucks and recreational vehicles), use the VEHTYPE and

SMPLSRCE variables found on the NHTS Vehicle File. 

• NHTS Vehicle File contains all vehicles and vehicle data collected from NHTS

survey respondents. 

CODEBOOK FOR EIA AUGMENTATIONS 

This section contains information on the variables in each of the two EIA data files:

household and vehicle data files. The codebook has been included first for household variables, 

followed by the codebook for the vehicle variables. 

For each variable the codebook provides: 

• variable name, this is the variable name used in the 2001 NHTS; 

• data level, either household- or vehicle-level data file; 

• type, numeric or character (alphanumeric) data 

• codes and descriptions, a description of every possible code identified with a 

variable; and, 

• label, a brief description of a variable. 

Table D2. Codebook for Public-Use Data Produced by EIA 

Variable

Name 

Data 

Level 

Type Codes

and 

Descriptions

Label 

1 AVGVEHS Household N Numeric values Number of vehicles in a household, expressed 

as vehicle-years, AVGVEHS 

2 CENSUS_D Household C “1” - New England 

”2” - Middle Atlantic 

”3” - East North Central 

”4” - West North Central 

”5” - South Atlantic 

”6” - East South Central 

”7” - West South Central 

”8” - Mountain 

”9” - Pacific 

Household Census Division, CENSUS_D 

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Table D2. Codebook for Public-Use Data Produced by EIA 

Variable

Name 

Data 

Level 

Type Codes 

and 

Descriptions

Label 

3 CENSUS_R Household C “1” - Northeast 

”2” - North Central 

”3” - South 

”4” - West 

Household Census Region, CENSUS_R 

4 DRVRCNTC Household N 1 - 1 driver

2 - 2 drivers 

3 - 3 drivers 

4 - 4 or more drivers 

EIA Number of drivers, DRVRCNTC

5 EHHWT# Household N Replicate weight values Replicate weight_#, EHHWT# 

6 EXPFLHHN Household N National sample weight values HH Weight-100% completed - NATL, 

EXPFLHHN 

7 HHCHILD Household N 0 - Households without children 

1 - Households with children 

EIA Household has children, HHCHILD

8 HHCOMP Household N 1 - Under 7 year, age of oldest 

child, household with children 

2 - 7 to 15 years, age of oldest 

child, household with children 

3 - 16 to 17 years, age of oldest 

child, household with children 

4 - Under 35 years, age of 

householder, one adult with no 

children 

5 - 35 to 59 years, age of 

householder, one adult with no 

children 

6 - 60 years or more, age of 

householder, one adult with no 

children 

7 - Under 35 years, age of 

householder, two or more adults 

with no children 

8 - 35 to 59 years, age of 

householder, two or more adults 

with no children 

9 - 60 years or more, age of 

householder, two or more adults 

with no children 

EIA Household composition, HHCOMP

ENERGY INFORMATION ADMINISTRATION/HOUSEHOLD VEHICLES ENERGY USE: LATEST DATA & TRENDS 167
APPENDIX D 

Table D2. Codebook for Public-Use Data Produced by EIA 

Variable

Name 

Data 

Level 

Type Codes

and 

Descriptions

Label 

9 HHINCOME Household N 1 - Less than $5,000 

2 - $5,000 to $9,999 

3 - $10,000 to $14,999 

4 - $15,000 to $19,999 

5 - $20,000 to $24,999 

6 - $25,000 to $34,999 

7 - $35,000 to $49,999 

8 - $50,000 to $74,999 

9 - $75,000 or more 

-9 - Don't know 

EIA Family income, HHINCOME 

10 HHR_HISP Household C “1” - Yes 

”2” - No 

Hispanic status of HH respondent, HHR_HISP 

11 HHR_RACEC Household N 1 - White

2 - Black 

3 - Other

EIA Race of householder, HHR_RACEC 

12 HHR_SEX Household C “1” - Male 

”2” - Female

Gender of HH respondent, HHR_SEX

13 HHSIZEC Household N 1 - One person 

2 - Two persons 

3 - Three persons 

4 - Four persons 

5 - Five persons 

6 - Six or more persons 

EIA Household size, HHSIZEC 

14 HHVEHLC Household N Numeric Values Filter variable for calculating estimates and std 

errors for household statistics, HHVEHLC 

15 HOUSEID Household C Character Values Household Identification Number, HOUSEID 

16 LIF_CYC Household C "01" - One adult, no children 

"02" - Two plus adults, no 

children 

"03" - One adult, youngest child 

0-5 

"04" - Two plus adults, youngest 

child 0-5 

"05" - one adult, youngest child 

6-15 

"06" - Two plus adults, youngest 

child 6-15 

"07" - One adult, youngest child 

16-21 

HH Life Cycle, LIF_CYC 

168 ENERGY INFORMATION ADMINISTRATION/HOUSEHOLD VEHICLES ENERGY USE: LATEST DATA & TRENDS
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Table D2. Codebook for Public-Use Data Produced by EIA 

Variable

Name 

Data 

Level 

Type Codes 

and 

Descriptions

Label 

"08" - Two plus adults, youngest 

child 16-21 

"09" - One adult, retired, no 

children 

"10" - Two plus adults, retired, no 

children 

17 PDRVAGEC Household N 1 - 16 to 17 years 

2 - 18 to 22 years 

3 - 23 to 29 years 

4 - 30 to 39 years 

5 - 40 to 49 years 

6 - 50 to 59 years 

7 - 60 to 69 years 

8 - 70 to 79 years 

9 - 80 years and over

-9 - Don't know 

EIA Age of primary driver, PDRVAGEC

18 PERCOSTC Household N 1 - Less than 2 

2 - 2 to 3.9 

3 - 4 to 5.9 

4 - 6 to 7.9 

5 - 8 or more

EIA Percent of income for motor fuel,

PERCOSTC 

19 POOR100 Household N Numeric values Households with incomes below 100 percent of 

the poverty level, POOR100 

20 POOR125 Household N Numeric values Households with incomes between 100 to 150 

percent of the poverty level, POOR125 

21 POOR150 Household N Numeric values Households with incomes above 150 percent of 

the poverty level, POOR150 

22 POORC Household N 1 - Below 100 percent 

2 - 100 to 150 percent 

3 - Above 150 percent 

-9 - Don't know 

EIA Income relative to poverty line, POORC 

ENERGY INFORMATION ADMINISTRATION/HOUSEHOLD VEHICLES ENERGY USE: LATEST DATA & TRENDS 169
APPENDIX D 

Table D2. Codebook for Public-Use Data Produced by EIA 

Variable

Name 

Data 

Level 

Type Codes

and 

Descriptions

Label 

23 SMPLSRCE Household C "01" - National Sample 

"02" - Baltimore Add-on 

"03" - Des Moines Add-on 

"04" - Hawaii Add-on 

"05" - Kentucky Add-on 

"06" - Lancaster PA Add-on 

"07" - New York Add-on 

"08" - Oahu Add-on 

"09" - Texas Add-on 

"10" - Wisconsin Add-on 

Sample where the case originated, SMPLSRCE

24 TOTBTUSINK Household N Numeric values Total household fuel consumed in units of 

1000 British Thermal Units (BTUs), 

TOTBTUSINK 

25 TOTCOST Household N Numeric values Household Expenditures, TOTCOST 

26 TOTCOSTC Household N 1 - $500 or less 

2 - $501 to $1,000

3 - $1001 to $1,500

4 - $1,501 to $2,000 

5 - $2,001 or more

EIA Motor fuel expenditures, TOTCOSTC 

27 TOTGALS Household N Numeric values Household gallon of gasoline equivalent,

TOTGALS 

28 TOTMILES Household N Numeric values Household vehicle miles traveled, TOTMILES

29 URBRUR Household C “1” - Urban 

”2” - Rural 

Household in urban/rural area, URBRUR 

1 BTUSINK Vehicle N Numeric values Fuel consumed in units of 1000 British 

Thermal Units (BTUs), BTUSINK 

2 COST Vehicle N Numeric values Motor fuel expenditures, COST

3 EHHWT# Vehicle N Replicates sample weight values Replicate weight_#, EHHWT# 

4 EIADMPG Vehicle N Numeric values EIA derived miles per equivalent-gallon,

EIADMPG 

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Table D2. Codebook for Public-Use Data Produced by EIA 

Variable

Name 

Data 

Level 

Type Codes 

and 

Descriptions

Label 

5 EIADMPGC Vehicle N 1 - 10.9 or less 

2 - 11 to 12.9 

3 - 13 to 15.9 

4 - 16 to 18.9 

5 - 19 to 21.9 

6 - 22 to 24.9 

7 - 25 to 29.9 

8 - 30 or More 

EIA Fuel economy, EIADMPGC 

6 EPATMPG Vehicle N Numeric values Unadjusted 55/45 combined fuel economy, 

EPATMPG 

7 EPATMPGF Vehicle C "10#" - represents a NHTS

sample vehicle that had a single 

model name "matching" to 

eligible NHTSA file records 

using four linking variables: 

vehicle manufacturer, vehicle 

model, vehicle model year, and 

vehicle type. 

"20#" - represents a NHTS

sample vehicle that had multiple 

model names "matching" to 

eligible NHTSA file records 

using four linking variables: 

vehicle manufacturer, vehicle 

model, vehicle model year, and 

vehicle type.

"30#" - represents a NHTS

sample vehicle that had a single 

model name "matching" to 

eligible NHTSA file records 

using three linking variables: 

vehicle manufacturer, vehicle 

model, and vehicle model year.

"40#" - represents a NHTS

sample vehicle that had multiple 

model names "matching" to 

eligible NHTSA file records 

using three linking variables: 

vehicle manufacturer, vehicle 

model, and vehicle model year.

Imputation flag for EPATMPG variable,

EPATMPGF 

ENERGY INFORMATION ADMINISTRATION/HOUSEHOLD VEHICLES ENERGY USE: LATEST DATA & TRENDS 171
APPENDIX D 

Table D2. Codebook for Public-Use Data Produced by EIA 

Variable

Name 

Data 

Level 

Type Codes

and 

Descriptions

Label 

"50#" - represents a NHTS

sample vehicle that "matched" to 

eligible NHTSA file records 

using three linking variables: 

vehicle manufacturer, vehicle 

type, and vehicle model year.

"600" - represents a "match"

based on EIA expert analysis

using subject matter experience,

in conjunction with past RTECS. 

Additionally, this imputation flag 

value represents recreation 

vehicles (VEHTYPE = “06”),

where MPG(EPA 55/45) has been 

fixed at a fuel economy rates 

based on the U.S. Department of 

Transportation, National 

Transportation Statistics 2000.

"001" - denotes a NHTS sample 

vehicle that was internally hotdecked to match with a median 

value of the Composite fuel 

economy defined by categories of 

one or more vehicle 

characteristics, such as make,

model, model year, and vehicle 

type. None of these imputed 

values were subsequently re-used 

in the actual hot-decking 

procedure of median values.

"999" - represents an imputation 

flag where no eligible NHTSA

file records were found to 

"match" a NHTS sample vehicle. 

* = For EPATMPGF codes, # is a number between 0 and 5. This number, #, represents a year increment. Due to the errors in 

respondents reporting accurate model year or, to a lesser extent, due to deficiencies in the NHTSA files, it was necessary to 

incrementally increase or decrease (not simultaneously increase and decrease) the model year for "matching" to successively

larger range of years. If, for example, an eligible match was not found for a NHTS sample vehicle having the following 

attributes: Volkswagen, Sirocco, 1990, Automobile. Toggling of model years, by a single year increase followed by a single

year decrease of the reported model year, resulted in a match with a Volkswagen, Sirocco, 1988, Automobile. In this example, 

the Volkswagen, Sirocco, 1990, Automobile, while seemingly a respondent reporting error, would receive an imputation flag of 

172 ENERGY INFORMATION ADMINISTRATION/HOUSEHOLD VEHICLES ENERGY USE: LATEST DATA & TRENDS
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Table D2. Codebook for Public-Use Data Produced by EIA 

Variable

Name 

Data 

Level 

Type Codes 

and 

Descriptions

Label 

"102" due to the "match" with the NHTSA file record corresponding to a Volkswagen, Sirocco, 1988, Automobile. 

8 EXPFLHHN Vehicle N Numeric national weight values HH Weight-100% completed - NATL, 

EXPFLHHN 

9 FUELTYPE Vehicle N 1 - Diesel 

2 - Natural gas 

3 - Electricity 

4 - Gasoline 

Type of transportation fuel, FUELTYPE

10 GALS Vehicle N Numeric values Motor fuel consumption, GALS 

11 ID11 Vehicle C Character Values HOUSEID plus VEHID, ID11 

12 MILES Vehicle N Numeric Values Vehicle miles traveled, MILES 

13 SMPLSRCE Vehicle C "01" - National Sample 

"02" - Baltimore Add-on 

"03" - Des Moines Add-on 

"04" - Hawaii Add-on 

"05" - Kentucky Add-on 

"06" - Lancaster PA Add-on 

"07" - New York Add-on 

"08" - Oahu Add-on 

"09" - Texas Add-on 

"10" – Wisconsin Add-on 

Sample where the case originated, SMPLSRCE

14 TVEHSHARE Vehicle N Numeric values (between 0 and 1) Prorated fraction of possession of vehicle, in 

vehicle-year, TVEHSHARE

15 VEHID Vehicle C Character values Vehicle ID number, VEHID 

16 VEHTYPE Vehicle C "01" – Passenger car

"02" - Vans (Large and Minivans)

"03" - Sport Utility Vehicle 

"04" - Pickup truck 

"06" - Recreational vehicle 

Type of vehicle, VEHTYPE

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APPENDIX D 

Table D2. Codebook for Public-Use Data Produced by EIA 

Variable

Name 

Data 

Level 

Type Codes

and 

Descriptions

Label 

17 VEHYEARC Vehicle N 1 - 2001 to 2002 

2 - 2000 

3 - 1999 

4 - 1998 

5 - 1997 

6 - 1996 

7 - 1995 

8 - 1992 to 1994 

9 - 1989 to 1991 

10 - 1986 to 1988

11 - 1983 to 1985

12 - 1980 to 1982

13 - 1977 to 1979

14 - 1976 or earlier

-9 - Don't know 

EIA Model year, VEHYEARC 

174 ENERGY INFORMATION ADMINISTRATION/HOUSEHOLD VEHICLES ENERGY USE: LATEST DATA & TRENDS
APPENDIX D 

Figure D2. Map of U.S. Census and Division Areas 

ENERGY INFORMATION ADMINISTRATION/HOUSEHOLD VEHICLES ENERGY USE: LATEST DATA & TRENDS 175