Case management in health and social service programs for older adults has evolved since the 1970s. This evolution reflects a changing public policy environment, a clearer appreciation of the challenges of living with chronic illness faced by older adults and their caregivers, and the development of a variety of approaches to financing and providing services across the full continuum of care, including primary, acute, in-home, community-based, and long-term services. As a result, case managers are located in hospitals, clinics, community agencies providing in-home services, Area Agencies on Aging, adult day care centers, and health maintenance organizations. Case managers may be employed in government programs, nonprofit community agencies, and for-profit service providers, or may be in private practice. They attempt to rationalize the system of care for older adults and their caregivers.
There has been considerable discussion about what is an appropriate name for case management. In some programs the case management function is called "care management," "care coordination," or "care planning." There is an ongoing concern that the term "case management," conveys an undesired sense of bureaucracy. Clients and caregivers have expressed their view that they "are not cases and do not want to be managed." Although widely used, the term "case management" remains unclear and confusing, describing benefit management, management of an acute event or of communitybased interventions, or other types of client management across the continuum of care.
The overall goal of care or case managers is to facilitate collaborative and cost-efficient interactions among providers that effectively integrate medical, psychological, and social services in order to provide timely, appropriate, and beneficial service delivery to the client. Such integration can encompass clients and their families, health care providers, community agencies, legal and financial resources, third-party payers, and employers (Gross and Holt).
At the most general level, case management can be defined as a coordinating function that is designed to link clients with various services based on assessed need. Case management has evolved in recognition of the fact that the fragmented and complex systems of care create formidable obstacles for older, disabled individuals and their families. There is a need for coordination of care because caregivers and chronically ill older persons may require services from several providers. Although operationalized in various ways, case management has a common set of core components that includes outreach, screening, comprehensive assessment, care planning, service arrangement, monitoring, and reassessment (Applebaum and Austin; White).
Outreach activities are designed to identify persons likely to qualify for and need health and social support services as well as case management. Case-finding efforts help ensure that eligible individuals are served. Screening is a preliminary assessment of the client's circumstances and resources to determine presumptive eligibility. Potential clients are screened by means of standardized procedures to determine whether their status and situation meet the program's target population definition. Accurate screening is critical. Effective outreach and screening are necessary for efficient program operation and management.
Comprehensive assessment is a systematic and standardized process for collecting detailed information about a person's physical, mental, and psychological functioning and informal support system that facilitates the identification of the person's strengths and care needs (Schneider and Weiss; Gallo et al.). Typically, comprehensive assessment focuses on physical health, mental functioning, ability to perform activities of daily living, social supports, physical environment, and financial resources. Many programs have adopted rigorous standardized multidimensional instruments.
Information collected during the assessment process is used to develop a plan of care. Care planning requires clinical judgment, creativity, and sensitivity as well as knowledge of community resources. Case managers consider the willingness and availability of informal caregivers to provide care. Balance between formal and informal services is a major consideration in the care planning process. Clients and caregivers participate in the process. The care plan specifies services, providers, and frequency of delivery. Costs of the care plan are also determined. Care planning is a key resource allocation process and is a critical case management function. Service arrangement involves contacting formal and informal providers to arrange services specified in the care plan. Case managers often must negotiate with providers for services when making referrals to other agencies. When they have the authority to purchase services on their clients' behalf, case managers order services directly from providers.
Case managers monitor changes in clients' situations and modify care plans to meet clients' needs. Ongoing monitoring combined with timely modification of care plans helps ensure that program expenditures reflect current client needs and are not based on outdated assessment data. Reassessment involves determining whether there have been changes in the client's situation since the last assessment. Systematic and regularly scheduled reassessment also helps in evaluating the extent to which progress has been made toward accomplishing outcomes specified in the care plan.
The nature of any case management service is defined and constrained by the program within which it is embedded (Beatrice; Applebaum and Austin). Therefore, many models of case management have been developed over time, reflecting changes in the goals of specific health and social service demonstration projects and programs designed to serve chronically ill older adults.
Case management in community-based long-term care programs developed in a series of demonstration projects between 1971 and 1985 (Kemper et al.; Applebaum and Austin; Cargano et al.). In 1971 no mechanism for funding in-home and community-based services was available, so it was necessary to identify funding to support the development of a community-based delivery system. Funds were made available through a waiver of the traditional restrictions imposed by the standard Medicare and Medicaid programs. This permitted the expenditure of funds for services provided outside of hospitals and nursing homes. These projects sought to demonstrate the development of a comprehensive and coordinated system of in-home and community-based services for older adults that would make available alternatives to premature or inappropriate nursing home placement. The projects also investigated whether communitybased services would cost less than nursing home care for eligible clients. Although these demonstrations differed in a variety of ways, they all included case management and an expanded array of in-home and community-based services. In these projects, case managers were nurses and social workers. They were responsible only for coordinating care plans that included in-home and community-based services. They had limited involvement with, and no authority in, the traditional health care system that provides primary, acute care, and skilled in-home nursing services.
Integrating health care
A basic flaw in the community-based long-term care demonstration projects was absence of health care services. Case managers could only develop care plans and coordinate covered community-based and in-home services. Clearly this approach does not adequately address the health care needs of older adults, who are major utilizers of health care services. In order to effectively address this reality, it was necessary to develop delivery systems that integrate services across the continuum of care, with particular attention to involving primary care physicians.
The Program of All-inclusive Care of the Elderly (PACE) and the Social Health Care Maintenance Organization (S/HMO) were developed to completely integrate services and financing for both acute- and long-term care services. Both programs incorporate a capitated payment for each participant, blending Medicare and Medicaid funds. In capitated programs, providers agree to provide a comprehensive package of services for a predetermined cost. This funding method introduces strong incentives for providers to establish cost containment mechanisms and to carefully monitor participant service utilization patterns. Case managers play a key role in these settings where providers have assumed financial risk.
PACE is based on the ON LOK program, which has been in existence in San Francisco since 1971 (Ansak). It is built on the adult day care model, and participants regularly attend a center where they receive primary care, and nursing, recreational, personal care, day health, preventive, rehabilitative, and social services. Case management in PACE involves an interdisciplinary team located on-site. Contracted services, which include hospital, nursing home, and specialist care, are also managed by the team. A team capable of effectively and efficiently managing the complex and changing needs of a frail population is composed of members who are strong in their specific disciplines, and have skills and attitudes that facilitate collaboration. Case management, as practiced by PACE teams, is focused on providing integrated health and social services within specific fiscal limits. The PACE model has been disseminated widely and has been implemented in diverse settings (Chin Hansen). The Balanced Budget Act of 1997 made PACE a permanent provider under Medicare and a state option under Medicaid, and authorized further expansion of the program.
The Social Health Maintenance Organization (S/HMO), which was launched in 1985, enrolls a cross section of Medicare-eligible persons. The program receives a capitated Medicare and Medicaid blended payment for each enrollee and assumes financial risk. All enrollees receive Medicare benefits. Frail clients also receive a limited long-term care supplement that is controlled by a case management unit composed of nurses and social workers.
Case management has been prominent in every S/HMO site. Case managers assess chronic care needs, authorize services for enrollees, and assist enrollees in obtaining noncovered services and benefits. S/HMO case managers coordinate service delivery and are responsible for facilitating continuity of care across the delivery system at key transition points, including hospital admission, hospital discharge, starting home care services, and nursing home placement.
S/HMO experience provided significant insights regarding physician involvement and highlighted the need to create policies and processes to enhance physician involvement in postacute care. In the original sites, primary care physicians were not consistently involved with their patients who were receiving long-term care benefits. (Leutz; Finch et al.). In addition, the S/HMO focused attention on the need to streamline assessment and more closely coordinate Medicare skilled care with community care benefits. S/HMO programs have demonstrated that enrollees benefit from efforts of case managers to maximize their care options.
Case management in Medicare
Older adults needing case management are often identified and assessed in the health care system. While chronic illness generates the greatest health care costs, medical management programs continue to focus primarily on managing acute events. Medicare beneficiaries in need of case management fall into two groups: individuals recently discharged from the hospital who have difficulty leaving home to receive needed services, and individuals receiving Medicare home health services. Medicare beneficiaries receive care through either the original fee-for-service Medicare program or through Medicare HMOs (Cassel et al.).
In the original fee-for-service Medicare program, an individual beneficiary's care is not formally coordinated among practitioners and providers involved in a case at any given time. In reality, postacute Medicare coverage and reimbursement policies serve to separate providers. There is no patient-centered case management mechanism. There is also the potential for inappropriate coordination where conflict of interest may influence care plan decisions.
From 1993 to 1995 the Health Care Financing Administration tested three different case management approaches in the original Medicare program. Although findings were mixed, case management was identified as a potentially useful service. Several factors were identified that could strengthen the case management function: full physician involvement in the care management process, highly focused goals and interventions, trained and experienced case management staff, and incentives to reduce or control Medicare costs (Foley).
The way Medicare reimburses postacute care providers will affect care management. In a cost-based reimbursement system, case managers provide assessment and coordination, and can act as a check on excessive utilization and disorganized service delivery. In a prospective payment system (Medicare risk in HMOs), case managers could facilitate beneficiary access to covered services by documenting care needs, assure appropriate communication of medical orders to providers, and make referrals for non-Medicare services.
In 1997 the Robert Wood Johnson Foundation convened an HMO Work Group on Care Management, which identified geriatric case management as an essential component for HMOs. The group, which included representatives from major health insurance companies and nationally recognized geriatricians, identified case management programs that HMOs should have in place to operate a successful Medicare risk program (Brummel-Smith). The group suggested the following components for the case management program: case selection (determining the need for intervention through information gathering), problem identification (assessing problems and potential interventions), planning (designing plans of care that reflect immediate, short-range, and ongoing needs and interventions), coordination (providing high-risk enrollees with appropriate and timely services), monitoring (periodic reassessment to determine necessary care plan modification), and evaluation (determining cost, quality of life, and quality of care outcomes). These are similar to the generic model of case management described earlier.
Whatever approach is adopted regarding case management in the original or Medicare risk programs, it will be necessary to address two basic considerations: the focus and scope of case management and the independence of case managers. These fundamental issues also apply to case management at any point on the continuum of care. While case managers may operate from a client/patient/beneficiary-centered approach, they will also be responsible for monitoring and controlling service utilization. They could also be responsible for making referrals and procuring both Medicare and non-Medicare services across the continuum of care from community resources. Medicare policy could also directly provide for and authorize access to case management itself.
Case managers' independence has two aspects, clinical and financial. There has been a continuing debate regarding the extent to which case management should be separated from the direct provision of services. A case manager who is not independent from a hospital, home health agency, nursing home, or community-based service provider may have a conflict of interest which affects his or her capacity to develop care plans that fully reflect the client's interests. Case managers face ethical dilemmas when their role creates conflict between advocating for clients and functioning as an agent for the delivery system that employs them (Browdie).
An innovation in publicly funded community-based long-term care services for older adults is consumer-directed care. Choice and control are key elements in this approach. Consumer direction ranges from the individual independently making all decisions and managing services directly, to using a designated representative to manage needed services. Although public long-term care programs generally employ case managers to arrange and monitor supportive services in the community, a number of programs provide significant opportunities for clients to direct their services rather than relying on case managers to do so.
The Cash and Counseling Demonstration (CCDE) is testing the direct cash payment approach to funding personal care assistance in the community. In the demonstration, Medicaid-eligible clients, having passed an initial screening, will be randomly assigned to the agencybased case management group (control) or to the cash option group (treatment). Persons assigned to the cash option group develop a care plan describing how they will use the funds. An assigned counselor approves the plan. If the care plan primarily involves hiring a personal care assistant, the consumer is then responsible for screening, hiring, scheduling, training, managing, and, if necessary, firing the assistant. The CCDE (based at the University of Maryland Center on Aging and evaluated by Mathematica) will provide important information and insights regarding the efficacy of agency-based, compared to consumerdirected, case management of personal care assistance (Simon-Rosinowitz et al.).
Case management is a response to the complexity and fragmentation of health and social service delivery systems. While there are common components, the practice of case management varies by setting. Although case managers assist with locating and coordinating services, the range of services they can coordinate and the options that are available will vary widely, depending on where on the care continuum the client is assessed as needing case management assistance. Any case management function reflects the program's financing and directly affects case manager's professional discipline, scope of client care, and manner of blending advocacy and cost containment responsibilities.
Carol D. Austin Robert W. McClelland
See also Adult Day Care; Consumer Directed Care; Day Hospitals; Health and Long-Term Care Program Integration; Home Care; Long-Term Care; Medicaid; Medicare; Social Services.
Ansak, M. "The ON LOK Model: Consolidating Care and Financing." Generations 14, no. 4 (1990): 73–74.
Applebaum, R., and Austin, C. Long Term Care Case Management: Design and Evaluation. New York: Springer, 1990.
The Balanced Budget Act of 1997. H.R. 2015. 105th Cong., 1st sess. Washington, D.C.: U.S. Government Printing Office, 1997.
Beatrice, D. "Case Management: A Policy Option for Long-Term Care." In Reforming the Long-Term Care System. Edited by J. Callahan and S. Wallack. Lexington, Mass.: D. C. Health Lexington Books, 1981. Pp. 121–162.
Browdie, R. "Ethical Issues in Case Management from a Political and Systems Perspective." Journal of Case Management 1, no. 3 (1992): 87–89.
Brummel-Smith, K. "Special Series: Geriatrics in Managed Care. Essential Components of Geriatric Care Provided Through Health Maintenance Organizations: The HMO Work Group on Care Management." Journal of the American Geriatrics Society 46, no. 2 (1998): 303–308.
Cargano, G.; Applebaum, R.; Christianson, J.; Phillips, B.; Thorton, C.; and Will, J. The Evaluation of the National Channeling Demonstration: Planning and Operation Experience of the Channeling Projects. Princeton, N.J.: Mathematica Policy Research, 1986.
Cassel. C.; Besdine, R.; and Siegel, L. "Restructuring Medicare for the Next Century: What Will Beneficiaries Really Need?" Health Affairs 18, no. 1 (1999): 16–24.
Chin hansen, J. "Practical Lessons for Delivering Integrated Services in a Changing Environment: The PACE Model." Generations 23, no. 2 (1999): 22–28.
Finch, M., Kane, R., et al. Design of the 2nd Generation S/HMO Demonstration: An Analysis of Multiple Incentives. Minneapolis: University of Minnesota Press, 1992.
Foley, L. Care Management: Policy Considerations for Original Medicare. Washington, D.C.: Public Policy Institute, American Association of Retired Persons, 1999.
Gallo, J.; Reichel, W.; and Anderson, L. Handbook of Geriatric Assessment, 2d ed. Gaithersburg, Md.: Aspen, 1995.
Gross, E., and Holt, E. Care and Case Management Summit Discussion Paper. Chicago: Foundation for Rehabilitation Education Research and National Association of Professional Geriatric Case Managers, 1998.
Kemper, P.; Applebaum, R.; and Harrigan, M. A Systematic Comparison of Community-Care Demonstrations. Madison: Institute for Research on Poverty, University of Wisconsin-Madison, 1987.
Leutz, W. "Five Laws of Integrating Medical and Social Services: Lessons from the United States and the United Kingdom." Milbank Quarterly 87, no. 1 (1999): 77–110.
Schneider, B., and Weiss, L. The Channeling Case Management Manual. Washington, D.C.: Assistant Secretary for Planning and Evaluation, Department of Health and Human Services, 1982.
Simon-Rusinowitz, L.; Mahoney, K.; and Benjamin, A. "Payments to Families Who Provide Care." Generations 22, no. 3 (1998): 69–75.
White, M. "Case Management." In The Encyclopedia of Aging. Edited by G. Maddox. New York: Springer, 1995. Pp. 147–150.
See Eye, aging-related diseases
Austin, Carol D.; McClelland, Robert W.. "Case Management." Encyclopedia of Aging. 2002. Encyclopedia.com. (June 29, 2016). http://www.encyclopedia.com/doc/1G2-3402200061.html
Austin, Carol D.; McClelland, Robert W.. "Case Management." Encyclopedia of Aging. 2002. Retrieved June 29, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3402200061.html
Case management assigns the administration of care for an outpatient individual with a serious mental illness to a single person (or team); this includes coordinating all necessary medical and mental health care, along with associated supportive services.
Case management tries to enhance access to care and improve the continuity and efficiency of services. Depending on the specific setting and locale, case managers are responsible for a variety of tasks, ranging from linking clients to services to actually providing intensive clinical or rehabilitative services themselves. Other core functions include outreach to engage clients in services, assessing individual needs, arranging requisite support services (such as housing, benefit programs, job training), monitoring medication and use of services, and advocating for client rights and entitlements.
Case management is not a time-limited service, but is intended to be ongoing, providing clients whatever they need whenever they need it, for as long as necessary.
Over the past 50 years, there have been fundamental changes in the system of mental health care in America. In the 1950s, mental health care for persons with severe and persistent mental illnesses (like schizophrenia , bipolar disorder , severe depression, and schizoaffective disorder ) was provided almost exclusively by large public mental hospitals. Created as part of a reform movement, these state hospitals provided a wide range of basic life supports in addition to mental health treatment, including housing, meals, clothing and laundry services, and varying degrees of social and vocational rehabilitation .
During the latter half of the same decade, the introduction of neuroleptic medication provided symptomatic management of seriously disabling psychoses. This breakthrough, and other subsequent reforms in mental health policy (including the introduction of Medicare and Medicaid in 1965 and the Supplemental Security Income [SSI] program in 1974), provided incentives for policy makers to discharge patients to the community and transfer state mental health expenditures to the federal government.
These advances—coupled with new procedural safeguards for involuntary patients, court decisions establishing the right to treatment in the least restrictive setting, and changed philosophies of care—led to widespread deinstitutionalization . In 1955 there were 559,000 persons in state hospitals; by 1980, that number had dropped to 132,000. According to the most recent data from the U.S. Center for Mental Health Services, while the number of mental health organizations providing 24-hour services (hospital inpatient and residential treatment) more than doubled in the United States from 1970 to 1998, the number of psychiatric beds provided by these organizations decreased by half.
As a result of deinstitutionalization policies, the number of patients discharged from hospitals has risen, and the average length of stay for newly admitted patients has decreased. An increasing number of patients are never admitted at all, but are diverted to a more complex and decentralized system of community-based care. Case management was designed to remedy the confusion created by multiple care providers in different settings, and to assure accessibility, continuity of care, and accountability for individuals with long-term disabling mental illnesses.
Models of case management
The two models of case management mentioned most often in the mental health literature are assertive community treatment (ACT) and intensive case management.
A third model, clinical case management, refers to a program where the case manager assigned to a client also functions as their primary therapist.
Assertive community treatment
The ACT model originated in an inpatient research unit at Mendota State Hospital in Madison, Wisconsin in the late 1960s. The program's architects, Arnold Marx, M.D., Leonard Stein, M.D. and Mary Ann Test, Ph.D., sought to create a "hospital without walls." In this model, teams of 10–12 professionals— including case managers, a psychiatrist , nurses, social workers , and vocational specialists—are assigned ongoing responsibility 24 hours a day, seven days a week, 365 days a year, for a caseload of approximately 10 clients with severe and persistent mental illnesses.
ACT uses multidisciplinary teams, low client-to-staff ratios, an emphasis on assertive outreach, provision of in-vivo services (in the client's own setting), an emphasis on assisting the client in managing their illness, assistance with ADL (activities of daily living) skills, emphasis on relationship building, and emotional support, crisis intervention (as necessary) and an orientation, whenever possible, towards providing clients with services rather than linking them to other providers.
Compared to other psychosocial interventions the program has a remarkably strong evidence base. Twenty-five randomized controlled clinical trials have demonstrated that these programs reduce hospitalization , homelessness , and inappropriate hospitalization; increase housing stability; control psychiatric symptoms; and improve quality of life, especially among individuals who are high users of mental health services. The ACT model has been implemented in 33 states.
Intensive case management
Intensive case management practices are typically targeted to individuals with the greatest service needs, including individuals with a history of multiple hospitalizations, persons dually diagnosed with substance abuse problems, individuals with mental illness who have been involved with the criminal justice system, and individuals who are both homeless and severely mentally ill.
A recent (2002) mail survey of 22 experts found that while intensive case management shares many critical ingredients with ACT programs, its elements are not as clearly articulated. Another distinction between intensive case management and ACT appears to be that the latter relies more heavily on a team versus individual approach. In addition, intensive case managers are more likely to "broker" treatment and rehabilitation services rather than provide them directly. Finally, intensive case management programs are more likely to focus on client strengths, empowering clients to fully participate in all treatment decisions.
Clinical case management
A meta-analytic study comparing ACT and clinical case management found that while the generic approach resulted in increased hospital admissions, it significantly decreased the length of stay. This suggests that the overall impact of clinical case management is positive. Consistent with prior research, the study concluded that both ACT and high-quality clinical case management should be essential features of any mental health service system. One of the greatest tragedies of deinstitutionalization has been that most families, without any training or support, often become de facto case managers for their family members.
Case management for children and adolescents
Case management is also used to coordinate care for children with serious emotional disturbances—diagnosed mental health problems that substantially disrupt a child's ability to function socially, academically, and emotionally. Although not a formal diagnosis in the Diagnostic and Statistical Manual of Mental Disorders (DSM), the handbook published by the American Psychiatric Association used by mental health professionals to diagnose mental disorders, the term "serious emotional disturbance" is commonly used by states and the federal government to identify children with the greatest service needs. While the limited research on case management for children and youth with serious emotional disturbances has been primarily focused on service use rather than clinical outcomes, there is growing evidence that case management is an effective intervention for this population.
Case management models used for children vary considerably. One model, called "wraparound," helps families develop a plan to address the child's individual needs across multiple life domains (home and school, for example). Research on the effectiveness of this model is still in an early stage. Another model, known as the children and youth intensive case management or expanded broker model had been evaluated in two controlled studies. Findings suggest that this broker/advocacy model results in behavioral improvements and fewer days in hospital settings.
In recent years, many case management programs have expanded their teams to successfully utilize consumers as peer counselors and family members as outreach workers. The programs have also been adapted to serve older individuals with severe and persistent mental illnesses. While the ACT model offers the strongest evidential base for its effectiveness, research into the clinical and service system outcomes of this and other models of case management is ongoing.
The effectiveness of any case management program depends upon the availability of high-quality treatment and support services in a given community, the structure and coordination of the service system, and on the ability of an individual or family to pay for care either through private insurance or (more often) through public benefit and entitlement programs. With recent policy directives from the Centers for Medicaid and Medicare Services (formerly the Health Care Financing Administration or HCFA) promoting the use of Medicaid funds for ACT, more states are funding case management through Medicaid. While some policy makers express concern about costs, the expense of these programs is usually offset by the savings realized from keeping patients out of jails, hospitals, and emergency rooms. Compared to traditional outpatient programs, case management also offers a level of care that is far more comprehensive and humane for a disabled population.
Manderscheid, Ronald W., Joanne E. Atay, María del R. Hernández-Cartagena, Pamela Y. Edmond, Alisa Male, and Hongwei Zhang. Chapter 14. "Highlights of Organized Mental Health Services in 1998 and Major National and State Trends." Mental Health, United States, 2000. Rockville, MD: U.S. Department of Health and Human Services, 1999. Available at: <http://www.mentalhealth.org/publications/allpubs/SMA01-3537/default.asp>.
Nathan, Peter E. and Jack M. Gorman, eds. A Guide to Treatments that Work. Second edition. New York: Oxford University Press, 2002.
U.S. Department of Health and Human Services. Mental Health: A Report of the Surgeon General. Rockville, MD: U.S. Department of Health and Human Services, 1999. <http://www.surgeongeneral.gov/library/mentalhealth/home.html>.
Dixon, Lisa. "Assertive Community Treatment: Twenty-Five Years of Gold." Psychiatric Services 51, no. 6 (June 2000): 759-765.
Schaedle, Richard, John H. McGrew, Gary R. Bond, and Irwin Epstein. "A Comparison of Experts' Perspectives on Assertive Community Treatment and Intensive Case Management." Psychiatric Services 53, no. 2 (February 2002): 207-210.
Ziguras, Stephen J. and Geoffrey W. Stuart. "A Meta-Analysis of the Effectiveness of Mental Health Case Management Over 20 Years." Psychiatric Services 51, no. 11, (November 2000): 1410-1421.
PACT across America. National Alliance for the Mentally Ill. (cited 7 April 2002). <http://www.nami.org/about/pact.htm>.
Irene S. Levine, Ph.D.
Levine, Irene S.. "Case management." Gale Encyclopedia of Mental Disorders. 2003. Encyclopedia.com. (June 29, 2016). http://www.encyclopedia.com/doc/1G2-3405700069.html
Levine, Irene S.. "Case management." Gale Encyclopedia of Mental Disorders. 2003. Retrieved June 29, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3405700069.html