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

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

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waiting time at locks were excluded from the trip times, but un<strong>for</strong>-<br />

tunatdly, time actually spent in locks could not be excluded.<br />

The range of variables was as follows:<br />

(1)Horsepower of towboat: 1400-3200<br />

(2) Length of flotilla: 350 feet-1180 feet<br />

(3)Breadth of flotilla: 35 feet-135 feet<br />

(4)Draft of flotilla: 1 foot-9.3 feet<br />

(5)Depth of water: 13.2 feet, 14.5 feet, and 18.3 feet<br />

(assumed)<br />

(6)Width of channel: 500 feet and 550 feet (assumed)<br />

(7)Stream velocity: 0.61 miles per hour-4.0 miles per<br />

hour (assumed).<br />

The values of the last three variables <strong>for</strong> each of the 224 observa-<br />

tions had to be assumed, <strong>for</strong> there were no data in the logs pertain-<br />

ing to depth, width, and stream velocity of the waterway. 14<br />

As be<strong>for</strong>e, predicted speed was regressed on actual speed with<br />

the following results:<br />

V f = 2.12 + 0.94Va<br />

(0.27) (0.06)<br />

in which (1) coefficient of determination = 0.49<br />

(2) standard error of estimation = 2.19<br />

(3) sample size = 224<br />

(4) standard errors shown in parentheses under the<br />

estimated coefficients.<br />

(4.20)<br />

In this case, as in the other, the slope coefficient is not signifi-<br />

cantly different from unity (t = 1) <strong>for</strong> any conventional level of<br />

significance. Of course, the intercept is significantly greater<br />

than zero (t = 7.85) which was to be expected since locking time was<br />

included in the average speed observations.<br />

These two sets of data fail to provide adequate tests of the hy-<br />

pothesis that the intercept term in the regression equations is zero,<br />

77

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