DRUID is an app for Android phones that measures impairment through a series of cognitive and physical tasks. DRUID measures reaction time, decision making, hand-eye coordination, balance, and time estimation, using divided attention tasks. And it takes just 2 minutes to test yourself once you have established a baseline.DRUID includes four different tasks or activities and gives the user an overall impairment score, as well as comparing the user's TEST scores (reaction time, etc.) to their (unimpaired) BASELINE score. DRUID is good at identifying when you are impaired; it does NOT, however, tell you if it is safe for you to drive. DRUID is a tool, and like any tool, even one as simple as a hammer, you need to practice it several times to get the most accurate results.