EIA Home > Transportation Home Page > The Denver Survey Methodology

The survey was designed to cover "fleets" of 10 or more cars, trucks or buses operated by a commercial company or local government agency out of one or more locations in the six county Denver/Boulder area.

Included:

1. the six counties surrounding Denver--Adams, Arapahoe, Denver, Douglas, Jefferson, and Boulder (the Denver nonattainment area as defined by the Clean Air Act)
2. all weight classes of highway vehicles: light-duty vehicles, light trucks/step vans, medium trucks, heavy trucks, and buses
3. purchased and leased vehicles
4. all types of businesses and local government agencies

Excluded:

1. employee-owned vehicles
2. short-term rental vehicles
3. vehicles in Federal or State government fleets
4. fleet vehicles that might operate within the area but do not operate out of a specific location or base in the area
5. vehicles being held for sale or lease

How the Target Population Was Identified

A twofold (dual frame) approach was taken to identify Denver-area fleets in the target population, from which a sample could be drawn. First a list of fleets was compiled from available commercial and private sources of fleet lists in the survey area. Added to this list were local government agencies, identified from municipal government directories. Second, a telephone screening survey was conducted using a list of all businesses in the survey area. This was designed to identify businesses that operated fleets, that might be missing from available lists of fleets.

How Survey Estimates Were Developed

Fleets from both frames were sorted into 10 strata, defined by the source of the fleets. A sample of fleets was selected for interview from each stratum. A total of 450 interviews were conducted with private companies that operated fleet vehicles, and 33 additional interviews were conducted with municipal government agencies that operated 10 or more vehicles. These 483 responses were weighted by the reciprocal of their probability of selection. This sampling weight was adjusted to account for an estimated 217 additional fleets, representing survey nonresponse. Based upon this adjusted sampling weight the survey estimated that there were 1,840 private fleets and 46 municipal goverment fleets operating out of the Denver/Boulder area as of the summer of 1995.

• Return to the Denver Clean-City Fleets Survey and view the survey data tables.
• See A Guide to Surveys of Motor-Vehicle Fleets. The Guide is a methodological report of the Clean City surveys conducted in Atlanta and Denver.

Top of Page