Three paramedics were boasting about improvements in their respective ambulance team’s response times. "Since we installed our new satellite navigation system," bragged one, "we’ve cut our emergency response time by ten percent."

"Not bad," the second paramedic commented. "But by using a computer model of traffic patterns, we we cut our average time by 20 percent."

"That’s nothing said the third paramedic. "Since our ambulance driver passed the bar exam, we’ve cut our emergency response time in half!"