Area Median Income
Area Median Income is the Median Household Income at the Region level.
Auto Ownership Costs
Auto Ownership Costs are defined using the AAA Your Driving Costs estimates, which include depreciation, insurance, taxes, license and registration, and finance charges (http://www.aaaexchange.com/Main/).
Autos
Autos, as defined by the US Census, include all passenger cars, vans, and pickup or panel trucks of 1-ton capacity or less kept at the home and available for the use of household members.
Auto Use Costs
Auto Use Costs are the costs associated with the actual amount of usage of automobiles. This value is made up of the miles driven, obtained from the transportation model VMT data, and the costs of that use, as defined by AAA Your Driving Costs estimates for cost per mile.
Average Block Size
Calculated in acres, Average Block Size is the average size of all the blocks making up a given block group. It is determined by dividing the total land area in a block group by the number of blocks composing the block group.
Average Monthly Ownership Costs
Average Monthly Ownership Costs represent the monthly costs for housing considering only owner-occupied housing units. Average Monthly Ownership Costs are calculated using the US Census variable of Selected Monthly Owner Costs. Selected Monthly Owner Costs are calculated from the sum of payment for mortgages, real estate taxes, various insurances, utilities, fuels, mobile home costs, and condominium fees (US Census).
Average Monthly Rent
Average Monthly Rent represents the monthly costs for housing considering only renter-occupied housing units. Average Monthly Rent is calculated using the US Census variable of Gross Rent. Gross rent is the contract rent plus the estimated average monthly cost of utilities (electricity, gas, water and sewer) and fuels (oil, coal, kerosene, wood, etc.) if these are paid by the renter (or paid for the renter by someone else). Gross rent is intended to eliminate differentials that result from varying practices with respect to the inclusion of utilities and fuels as part of the rental payment (US Census).
Block Group
A subdivision of a census tract, a Block Group is the smallest geographic unit for which the Census Bureau tabulates sample data. All data utilized in the H+T Index, unless otherwise noted, is calculated and modeled at the block group level.
Carbon Dioxide (CO2) Emissions
Carbon dioxide is generated as a by-product of the combustion of fossil fuels or the burning of vegetable matter, among other chemical processes. Here, we refer to the CO2 emissions resulting from private automobile use.
Census
The census of population and housing, taken by the Census Bureau in years ending in 0 (zero). Article I of the Constitution requires that a census be taken every ten years for the purpose of reapportioning the U.S. House of Representatives (US Census).
Consolidated Metropolitan Statistical Area (CMSA)
A geographic entity defined by the federal Office of Management and Budget for use by federal statistical agencies. An area becomes a CMSA if it meets the requirements to qualify as a metropolitan statistical area, has a population of 1,000,000 or more, if component parts are recognized as primary metropolitan statistical areas, and local opinion favors the designation (US Census).
Cost Burden
A Cost Burden represents an expenditure as a percent of the Area Median Income.
Data Not Available (DNA)
Data Not Available indicates block groups in which data were unable to be estimated or modeled.
Employment Access Index
Employment Access Index is a measure developed by CNT to estimate both the quantity of and residentsÕ access to the jobs in a region. It is calculated using an inverse-square law to model total access to jobs in the metropolitan area by using the sum of the number of jobs divided by the square of the distance to those jobs.
Federal Transit Administration (FTA)
FTA is one of 11 operating administrations within the U.S. Department of Transportation. FTA provides stewardship of combined formula and discretionary programs to support a variety of locally planned, constructed, and operated public transportation systems throughout the U.S., including buses, subways, light rail, commuter rail, streetcars, monorail, passenger ferry boats, inclined railways, and people movers (http://www.fta.dot.gov/).
Fuel Efficiency
Fuel Efficiency refers to the amount of work obtained from the amount of fuel consume. Here, in reference to automobiles, an average fuel efficiency figure of 20.3 mpg has been utilized.
Gasoline Expenditures
Gasoline Expenditures refers to the amount of money spent by a household on gasoline in a given period of time.
Household (HH)
A Household includes all the people who occupy a housing unit as their usual place of residence (US Census).
Housing Costs
Housing Costs represent the average cost of housing for a given block group. Here, housing costs are calculated as an average of Monthly Ownership Costs and Monthly Rent factoring the percentage of owner occupied housing units versus renter occupied housing units obtained from the US Census.
Location Efficiency
Location Efficiency recognizes the inherent efficiency of a place. Compact neighborhoods with an interconnected street network, access to transit, mixed land uses, and concentration of retail and services, are highly efficient communities. When brought together, these elements enable an efficiency of scale Broad transportation choices and high access to key destinations that contribute to a vibrant and healthy life are enhanced in such neighborhoods. These neighborhoods require less time, money, and greenhouse gas emissions for residents to meet their everyday travel requirements, and thus have high location efficiency. An interconnected street network is vital to location efficiency; it links housing to retail and transit,. It not only allows for more efficient car movement - but it is equally inviting to pedestrians by providing the choice to walk or take transit to their destination, rather than drive.
Household Density
Household Density is defined as households per residential acre. Residential acres are determined using the constituent blocks in a block group where there is at least one household per acre. The count of total occupied housing units from the US Census is then divided by this derived residential land area.
Median Household Income:
Household Income includes the income of the householder and all other individuals 15 years old and over in the household, whether they are related to the householder or not. This value represents the median at the block group level. Although the household income statistics cover calendar year 1999, the characteristics of individuals and the composition of households refer to the time of enumeration (April 1, 2000). Thus, the income of the household does not include amounts received by individuals who were members of the household during all or part of calendar year 1999 if these individuals no longer resided in the household at the time of enumeration. Similarly, income amounts reported by individuals who did not reside in the household during 1999 but who were members of the household at the time of enumeration are included. However, the composition of most households was the same during 1999 as at the time of enumeration (US Census).
Metric Ton
A Metric Ton is a common international measurement for the quantity of greenhouse gas emissions. A metric ton is equal to 2205 lbs or 1.1 short tons.
Metropolitan Statistical Area (MSA)
A geographic entity defined by the federal Office of Management and Budget for use by federal statistical agencies, based on the concept of a core area with a large population nucleus, plus adjacent communities having a high degree of economic and social integration with that core. Qualification of an MSA requires the presence of a city with 50,000 or more inhabitants, or the presence of an Urbanized Area (UA) and a total population of at least 100,000 (75,000 in New England). The county or counties containing the largest city and surrounding densely settled territory are central counties of the MSA. Additional outlying counties qualify to be included in the MSA by meeting certain other criteria of metropolitan character, such as a specified minimum population density or percentage of the population that is urban. MSAs in New England are defined in terms of minor civil divisions, following rules concerning commuting and population density (US Census).
Miles per Gallon (MPG)
Miles per Gallon refers to the distance traveled in a vehicle powered by one gallon of fuel.
Public Transit Costs
Public Transit Cost is calculated as the average transit ridership for a block group multiplied by the É
Public Transportation (Transit)
As defined in the Federal Transit Act, Public Transportation is "transportation by a conveyance that provides regular and continuing general or special transportation to the public, but does not include school bus, charter, or intercity bus transportation or intercity passenger rail transportation provided by the entity described in chapter 243 (or a successor to such entity)." (http://www.ntdprogram.gov/ntdprogram/Glossary.htm#P)
Region
Regions are defined as the federal Office of Management and Budget (OMB) metropolitan areas as utilized in the 2000 US Census. For this research, metropolitan statistical areas (MSAs) and consolidated metropolitan statistical areas (CMSAs) were utilized.
Transit Connectivity Index (TCI)
The Transit Connectivity Index (TCI) was developed by CNT as a measure of transit service. Transit service levels for the purposes of the TCI are based on the access and intensity of transit service in a given Census block group. Access is captured by a quarter mile buffer around each bus stop, a half mile buffer around each rail station, and a half mile buffer around each ferry; intensity is based on the number of lines that serve the Census block group. For a given Census block group, the index accounts for the percentage of land area within walking access to a transit route and the number of lines available. It is important to note that TCI is not a descriptive or a literal definition of service, but rather a calculated prediction of transit service levels.
Transportation Costs
Transportation Costs represent the total cost of household transportation. Here, transportation costs are defined as the sum of auto ownership costs, auto use costs, and public transit costs.
Travel Time to Work
Travel Time to Work, calculated in minutes, refers to the total commute time. From the US Census, this value represents the time it usually takes a person to get from home to work each day. The elapsed time includes time spent waiting for public transportation, picking up passengers in carpools, and time spent in other activities related to getting to work.
Vehicle Miles Traveled (VMT)
Vehicle Miles Traveled represents the average annual auto travel by a certain entity. This includes commute travel, but also all other daily auto trips.
Worker
Workers are defined using the Census variable Employed. Employed includes all civilians 16 years old and over who were either (1) "at work" — those who did any work at all during the reference week as paid employees, worked in their own business or profession, worked on their own farm, or worked 15 hours or more as unpaid workers on a family farm or in a family business; or (2) were "with a job but not at work" — those who did not work during the reference week but had jobs or businesses from which they were temporarily absent due to illness, bad weather, industrial dispute, vacation, or other personal reasons. Excluded from the employed are people whose only activity consisted of work around the house or unpaid volunteer work for religious, charitable, and similar organizations; also excluded are people on active duty in the United States Armed Forces (US Census).
The H+T Index preselected map comparison shows Housing Costs as Percent of Income compared to Housing and Transportation Costs as Percent of Income. 
The Gas Cost Impacts preselected map comparison shows Annual Household Gasoline Expenditures comparing 2000 to 2008.
The Greenhouse Gas Impacts preselected map comparison shows Carbon Dioxide Emissions from Household Auto Use, with the first maps showing Emissions per Acre and the second map showing Emissions per Household.
Here, you can pick any two variables that you'd like to see compared. Consider: How does Household Density compare to Transportation Expenditures? Are Carbon Dioxide Emissions lower where the Transit Connectivity Index is higher?
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Summary Table of Statistics:
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Line-Graph Showing Correlation to H, T, and H+T:
