produce and ornamentals passing through the Florida Agricultur-
al Inspection Station on U.S. Interstate 95. In March and
June, 198 and 215 interviews were completed, respectively. The
interviewing was performed from 5:00 PM to midnight on each of
the days (when most of the outbound truck passing occur).
Very specific questions were asked regarding the rates re-
ceived, cargoes, and service characteristics of the currently
carried load, as well as certain characteristics of the carrier
(see Appendix 2). To avoid selection bias, during the inter-
view period all truckers carrying produce and ornamentals were
interviewed. The interview strategy employed had an added
advantage in that the quality of the information obtained
should be high for two reasons.5 First, the shipping documents
could be examined (they are temporarily surrendered by the
truckers during the inspection process) and, second, truckers
were questioned about current or just past events. With only 5
truckers refusing to be interviewed, the response rate was,
essentially, 100 percent. A summary of responses is presented
in Table 3.




 THE RESULTS


 In Table 4, the results of the estimation process are
presented. The Goldfeld-Quandt test for heteroskedasticity
across distance (D and DSQ) and DAYLOSS was carried out, but
none was indicated.6 The equation explains 58 percent of the
variation in PT as indicated by the coefficient of determina-
tion. Moreover, all parameter estimates have the theoretically
anticipated signs or have standard errors which are large rela-
tive to the absolute value of the estimated paramter.

 The estimated parameter associated with the June intercept
shifter is positive and over four times the magnitude of its
standard error, indicating a tighter truck supply situation in
June than in March. This is not surprising when it is consid-