Q2 Z2,(Q2) Z2(Q2) - Institute for Water Resources - U.S. Army

equation has by far the worst fit of the nine regressions-with an R 2
value of .460, down from .986 in the logarithmic equation, with all
three parameter estimates insignificant.
The urban concentration coefficients came out negative as expected
in all but one case. However, only three of the nine estimates were
statistically significant.
All in all Benishay and Whitaker's parameter estimates appear quite
reasonable, most of them - confirming our a priori expectations as to sign
and size. Total ton-miles for each transport mode tend to increase with
national production and to decrease with average rates as we would ex-
pect. Since their interest was in national demands individual flows
were not considered; however, their reluctance to include the quality
variable, speed, and rates of the competing modes is regrettable. This
latter point, the investigation of the cross modal rate effects, is
Considered in the remaining studies.
The next article to be discussed is by A. Hurter. 13 He begins by
observing that the demand for the services of inland waterway carriers
depends primarily on two things: (1) the demand for the kinds of goods
which are shipped on the waterways; and (2) the share of this demand
carried by waterway carriers. Hurter sees his efforts as explaining
the aggregate imports and exports for all regions of the United States
and for the region covered by Mississippi River carriers that take place
by barge.
13. A. P. Hurter, Jr., "Some Aspects of the Demand for Inland Waterway
Transportation," The Economics of Inland Waterway Transportation,
The Transportation Center, Northwestern University, 1965.
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