A (http://about.usps.com/newsroom/service-alerts/) full list of three-digit zip codes
affected by the mail cancelation include:
(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.
map contains more than 6.7 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.S.
From a practical point of view, firms maintain sales data by customer address and they can easily group customer sales into the 900 three-digit zip codes. (Clustering customers into smaller units of five-digit and nine-digit zip codes was not considered.) 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.
One such system would define payment areas within MSAs using five-digit ZIP Codes as boundary lines and within rural areas using three-digit ZIP Codes. This approach would reserve the precision of individual five-digit ZIP Codes for more populated MSAs, where most HMOs operate, and where market conditions may be most heterogeneous.
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.