Group hopes purchasing power or members will spark changes. What happens when big health care purchasers like AT&T, Boeing, Caterpillar, Delta Airlines, Eli Lilly, Ford, General Motors, and IBM get together and voice an opinion about the quality of health care? Hospitals listen. At least that's the theory behind the Leapfrog Group, an organization sponsored by the Business Roundtable and including some 70 companies that hope to improve safety in health care by alerting patients to key features of hospitals around the country.