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

egressions are also run for each of the five principal AAR commodity
classes. 14
Some of the results Hurter obtains, as will be indicated below,
are quite good; some, however, are peculiar. The estimates of price
elasticities for the "all waterway carriers" group come out with wrong,
i.e., positive, signs. Such a result suggests that as the price of
barge service increases more tonnage is carried by barge. In the rail
equations a large number of the crots price elasticities have the wrong,
in this case negative, sign. These estimates, however, are never sta-
tistically significant. By far the best results obtained were for
water carriers operating on the Mississippi River system. These will
be discussed in somewhat greater detail.
For this river system he begins by determining the main commodities
carried by barge. This information is summarized in Table 2.1. We
see that Groups I, III and V comprise more than 98 percent of the total
tons transported and total revenue earned by the system carriers. Table
2.2 summarizes Hurter's price elasticity estimates for Mississippi River
carriers, and for the rail carriers for the three main commodity groups.
None of the price elasticity estimates for Products of Agriculture
carried by water are significantly different from zero. They do, how-
.
ever, all have the right sign. The parameter estimates for Products of
Mines and Manufactures all have the proper sign and all but one are
statistically significant.
14, The Association of American Railroads' commodity classification
approved by the Interstate Commerce Commission for reporting purposes
during these years recognized five principal commodity classes:
• •
I. Products of Agriculture
• Animals and Products
III. Products of Mines
IV. Products of Forests
V. Manufactures and Miscellaneous Products
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