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.
The three-digit ZIP codes
with the most fraud rings observed are areas around Washington DC; Tampa, Fla.
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.
Another variant of the use of three-digit ZIP Codes is to use them to configure rural areas, while urban areas are defined in accordance with population-density criteria.
In the days after Hurricane Katrina, postal service to eight three-digit ZIP codes
in Louisiana and Mississippi was suspended, impacting over 750,000 subscribers across 360 magazine titles served by CDS.