Unformatted text preview: BEYOND THE CLASS 3.1 | LEARNING OUTCOMES 1 AND 2
Sensitivity and Specificity
LOOKING AGAIN AT FIELD SOBRIETY TESTS (FSTS)
There are three common testing procedures implemented during an
HGN: Horizontal Gaze Nystagmus
OLS: One-Leg Stand
WAT: Walk and Turn
In other activities in this workbook, we looked at the OLS and came
up with our own scoring mechanism. However, it is more typical
to be scored on a scale of 0 to 9 on each of these three testing
procedures. And in practice, officers will often consider that a
score of 2 or higher in any of the three testing procedures means
that you are drunk and can lead to an arrest for DUI.
However, for this assignment we will be looking once again at total FST scores. We will use those scores
to practice doing false positive and false negative calculations and to see what happens as the criteria
DATA AND AN EXAMPLE
We are going to be working with data from the NHTSA's 1998 San Diego field sobriety test validation
study. This study was published by the NHTSA as the report "Validation of the Standardized Field
Sobriety Test Battery at BACs Below 0.10%" by Drs. Jack Stuster and Marcelline Burns. A copy of the
data set, ordered by total FST, is included in the Appendix. There are 296 subjects in the study (and in
Let's assume that a BAC of 0.04% or above means you are actually drunk. That won't change for this
Suppose we say that a total FST (that is, a sum of one's HGN, OLS, and WAT scores) of 2 or more means
a person is drunk. The 296 subjects in the study would be categorized as shown in Table 3.26 below.
Make sure you know where these numbers came from.
TABLE 3.26 Using Total FST 2 2 to Designate "Drunk"
BEYOND THE CLASS 3.1
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- Fall '12