In the homeowners' insurance study, the researchers were interested in examining whether dwellers in different locations received the same treatment when shopping for insurance. Contact with the state insurance office and insurance industry groups yielded no information below the city level. Therefore, the information was of no use when trying to detect differences within the city.
Coffin, Peggy and Ruff, Jack, "Homeowner Insurance Availability and Cost in Omaha" (1983). Publications. 192.