4) Our sample includes 133 unique three-digit zip codes with at least five corporate headquarters.
We show that a firm's CSR policy is significantly influenced by the CSR policies of firms in the same three-digit zip code, an effect possibly due to investor clienteles, local competition, and/or social interactions.
We find that a firm's corporate social responsibility (CSR) policy is significantly influenced by the CSR policies of firms in the same three-digit zip code, an effect possibly due to investor clientele, local competition, and/or social interactions.
Marshall & Swift produces the indices monthly for three-digit zip codes
throughout the country.
CMS has stated in final regulations that a state can divide itself into rating areas based on county boundaries, on three-digit ZIP codes
, or on a division between metropolitan statistical areas (MSAs) and other areas.
7 million miles of routable roads and six types of geographic boundaries -- states, counties, metropolitan statistical areas, three-digit ZIP codes
, five-digit ZIP codes and 2000 U.
These three-digit zip codes provided a first level of demand clustering in a firm's data base.
For this study, 1990 population estimates by three-digit zip codes nationwide were obtained from the National Planning Data Corporation.
This author agrees with the general nature of the approach and formulates the following specific clustering procedure: Beginning with 900 three-digit zip codes (or clusters), and their associated latitude-longitude coordinates, the great circle distances, corrected for road distances, are computed for all zip code pairs.
For this reason, Milliman and Robertson (1983, 1987) suggested that Medicare base its payments to HMOs on three-digit ZIP Codes.
In rural areas, three-digit ZIP Codes areas should be much less vulnerable to payment-rate instability than would sparsely populated five-digit ZIP Code areas.