In 1990, the Supreme Court ruled that sobriety checkpoints are legal, but police departments must file a plan that describes how they will randomly select drivers for sobriety tests. Florida Highway Patrol troopers, Pasco Sheriff’s deputies, and Tarpon Springs Police officers filed a plan for a sobriety checkpoint in New Port Richey, Florida, stating that they would pull over every third car.
a. What type of sampling did the police department plan to use? Explain.
b. A police officer’s squad car video showed that 29 of 49 vehicles were pulled over at the New Port Richey checkpoint between 12:16 a.m. and 12:33 a.m. on December 17, 2011. What proportion of vehicles was pulled over? Round your result to the third decimal place.
c. A driver arrested at the checkpoint for drunk driving contested the case in court. He argued that the police did not follow the law. Explain why it makes sense his case was dropped.