For most people, picking a doctor is hardly a scientific process. They ask friends or family members to pass along names of doctors they like and trust, or rely on another doctor's referral. Increasingly, health plans and independent groups are making physician information available online to help consumers make these choices more methodically. But experts caution that most doctor-rating systems are still rudimentary, and a four-star rating or other high-performance designation may not reliably reflect a doctor's abilities. While ratings can provide helpful information, consumers still need to dig a little to find the best doctors for their needs.