Margaret M. Conwell, 61, who supervised a number of studies of mental health programs around the country as a biostatistician at the National Institute of Mental Health, died of cancer Wednesday at the Deaconess Hospital in Boston.

Mrs. Conwell, who retired from NIMH last year and moved to Hull, Mass., was born in Boston, graduated from Radcliffe College, where she majored in biology and chemistry, and earned a master's degree in education at Boston Teachers College. She did graduate work in psychology at Boston University and at the Harvard University School of Public Health.

In 1951, she and Dr. Warren T. Vaughn published a survey of community psychiatric resources in Massachusetts. The study is said to have set a pattern for similar reviews elsewhere in the country.

Following her marriage in 1954 to Dr. Donald P. Conwell, Mrs. Conwell lived in New Orleans, where she was a school teacher, in Louisville, Ky., and in Naples, Italy, where she was a faculty and guidance counselor at the American School while her husband was a U.S. Public Health Service Officer assigned to the U.S. Consulate there.

In 1962, the Conwells moved to Washington and Mrs. Conwell began her career at the National Institute of Mental Health. She supervised publication of the first federal analytical survey of mental health facilities that provide outpatient as well as residential care. As was the case in other studies she conducted, the focus was on the effectiveness of the care and its cost.

In cooperation with the American Psychiatric Association, Mrs. Conwell undertook the first nationwide review of private psychiatric practices. She helped develop standards for the old Department of Health, Education and Welfare for the funding of health care and the review of professional qualifications for staff members of mental health facilities.

In 1974, she organized a survey of residential treatment centers for youngsters with mental ailments. The study involved the training of more than 60 psychiatrists, psychologists and psychiatric nurses and social workers. tThe project was funded by the Defense Department for the Comprehensive Health and Medical Program for the Uniformed Services.

Mrs. Conwell was a member of the American Public Health Association and was active in its mental health section.

Her marriage to John Devitt ended in divorce.

In addition to her husband, of Hull, survivors include a son by her first marriage, John E. Conwell, also of Hull; two sisters, Helen M. Keyes of Cambridge, Mass., and Frances M. Keyes of Hull, and one brother, Frederick A. Keyes Jr. of Minneapolis.