I__. - International Military Testing Association

the order they were obtained. FoLLowing the alcohoL challenge, perEormance
dropped dramatically on all subtests, then recovered, in most cases in a
monotonic or near monotonic Eunction, as determined by BAL during the period
of alcohol metabolism. If one were to choose a single subtest to index BAL,
Code Substitution would be a likely candidate. For this test it can be seen
that each change of one hundredth of a percent BAL is indexed by a change of
approximately 1.5 points on the code Substitution task.
Figure 1. Code Substitution Number Correct for
Baseline and Blood Alcohol Levels As Shown
Formulation of the Quantitative Dose Equivalency Model
Multiple regression was used to develop scores that maximally predicted
BAL. The multiple regression between BAL as predicted from all nine surrogate
battery subtests was 0.77. Subsequent stepwise regression analysis revealed
that an optimally selected subset of only four oE the subtests produced a
multiple R of 0.765; therefore, virtually no loss in predictive power resulted
from use of the shortened battery. When this latter coefficient is corrected
for shrinkage, R equalled 0.75; therefore, 57% of the variance in blood
alcohol is predictable from the four subtest battery. The resulting
regression equation (simplified by rounding to whole numbers) is shown in
Equation (1):
BAL = 0.3 - (9CS+2GR+SMP+6TFT)/lOOO, (1)
where CS, GR, Mp, and TFT, refer to percent decrement from baseline of Code
Substitution, Grammatical Reasoning, Math Processing, and Two-Finger Tapping,
respectively.
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