By combining HGN and WAT, what percentage accuracy can be achieved?

The combination of Horizontal Gaze Nystagmus (HGN) and Walk-and-Turn (WAT) tests provides a high level of accuracy in predicting whether a driver is impaired due to alcohol. When these two specific standardized field sobriety tests are utilized together, studies have shown that the accuracy can reach approximately 80%. This percentage reflects the effectiveness of both tests in evaluating a driver's coordination, balance, and eye movement, which are commonly affected by alcohol intoxication.

The HGN test focuses on involuntary eye movements, while the WAT evaluates physical coordination, attention, and the ability to follow instructions. When law enforcement combines these assessments, they gather more comprehensive evidence, increasing the likelihood of accurately identifying a driver who is under the influence. Thus, achieving an 80% accuracy rate through this combination is in line with research findings on the effectiveness of standardized field sobriety tests.