You will be given a definition of a task first, then some input of the task.
In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

Context: Despite the growth of managed care in the United States, there is little information about the arrangements managed-care plans make with physicians.', 'In 1994 we surveyed by telephone 138 managed-care plans that were selected from 20 metropolitan areas nationwide. Of the 108 plans that responded, 29 were group-model or staff-model health maintenance organizations (HMOs), 50 were network or independent-practice-association (IPA) HMOs, and 29 were preferred-provider organizations (PPOs).', "Respondents from all three types of plan said they emphasized careful selection of physicians, although the group or staff HMOs tended to have more demanding requirements, such as board certification or eligibility. Sixty-one percent of the plans responded that physicians' previous patterns of costs or utilization of resources had little influence on their selection; 26 percent said these factors had a moderate influence; and 13 percent said they had a large influence. Some risk sharing with physicians was typical in the HMOs but rare in the PPOs. Fifty-six percent of the network or IPA HMOs used capitation as the predominant method of paying primary care physicians, as compared with 34 percent of the group or staff HMOs and 7 percent of the PPOs. More than half the HMOs reported adjusting payments according to utilization or cost patterns, patient complaints, and measures of the quality of care. Ninety-two percent of the network or IPA HMOs and 61 percent of the group or staff HMOs required their patients to select a primary care physician, who was responsible for most referrals to specialists. About three quarters of the HMOs and 31 percent of the PPOs reported using studies of the outcomes of medical care as part of their quality-improvement programs.\Question: Do a national survey of the arrangements managed-care plans make with physicians?
Output:
Managed-care plans, particularly HMOs, have complex systems for selecting, paying, and monitoring their physicians. Hybrid forms are common, and the differences between group or staff HMOs and network or IPA HMOs are less extensive than is commonly assumed.