APPENDIX A

COMBINED TEST SCORING PROCEDURE

[Post-publication note (August 1999): This matrix is no longer used in SFST training materials.]

Horizontal Gaze Nystagmus Test Score

0

1

2

3

4

5

6

Walk

0

  

  

 

1

  

  

 

&

2

 

 

 

 

3

 

 

 

 

 

Turn

4

 

 

 

 

 

5

 

 

 

 

 

Test

6

 

 

 

 

 

 

 

7

 

 

 

 

 

 

  

Score

8

 

 

 

 

  

 

  

9

 

 

 

 

 

 

 

   

The above matrix utilizes the combined test scores for the horizontal gaze nystagmus test and the walk and turn test. If the box at the intersection of a subjectís horizontal gaze nystagmus and walk and turn test scores is shaded, a subjectís blood alcohol content is predicted to be .10%. Data showed that the accuracy of law enforcement officers correctly classifying subjects as above or below .10% blood alcohol content is 80% using this matrix.