USPS justifies its projection on the grounds that “the technology used by mailers
today is dramatically more sophisticated than that of the 1960’s, when the 5-digit ZIP code was introduced. The widespread use of the 5-digit ZIP code, the proliferation of
office automation and automated mailings, successful and accelerated acceptance of ZIP+4."
and the ZIP+4 incentive (USPS, Jellison, 1984c). In
all point to 1983, GAO
reviewed the one by R.H. Bruskin
ZIP+4 market study cited by Associates). GAO expressed
USPS (a 1982 survey conducted for USPS reservations about the study methodology
(response rate too low, study universe not representative) study results (GAO, 1983b, pp. iv-v, 31-36).
After reviewing all available evidence, OTA concluded that the USPS ZIP+4 projection should be considered optimistic, that inappropriate median estimate would be the 5-digit ZIP growth pattern, and that an appropriate pessimistic estimate would be a growth pattern similar to that of the USPS Electronic Computer Originated Mail Service
(E-COM), time, the
where actual usage was first year ZIP+4 usage
one-third turn out
USPS projections. At the present
estimated 2.73 billion pieces of ZIP+4 first class mail at year end 1984 represents about 5.4 percent of the target mail base as compared to about 7 percent under the pessimistic scenario, 13 percent under the median, and 28 percent under the optimistic scenario.
OTA’s ZIP+4 growth curves are shown in figure 7. OTA assumed that there is a 5 percent chance that actual ZIP+4 usage will equal or exceed the USPS projection (the high growth curve), a 50-50 chance that actual usage will be above or below the median growth curve (that is, it is equally likely that ZIP+4 usage will be above or below the 5- digit ZIP growth curve), and a 5 percent chance that ZIP+4 usage will be equal to or less than the low growth curve. At the present time, ZIP+4 growth is tracking a growth curve lower than the low curve in figure 7.