"SPC programs involve employees at many levels, from plant-floor operators who run the machines all the way to the management types who make decisions about capital resources," says Jeffry Cawley, vice president of Northwest Analytical Inc., a supplier of SPC software. "With each group, you encounter resistance for different reasons."

Plant-floor operators often have limited computer skills and little exposure to statistics. Cawley advises supervisors to help their employees overcome their math and computer phobia before it derails the SPC program.