41.   The study is based on two telephone surveys conducted earlier this year.

42.   The study was based on analysis of air samples collected at various locations in the Los Angeles metropolitan area during a one-year period.

43.   The study was based on monthly Department of Transportation statistics.

44.   The study was based on visits to care centers before and after Florida passed legislation tightening staffing requirements.

45.   The study is based on nationwide figures compiled by the U.S. Department of Commerce and the Federal Reserve.

46.   The University of Texas study was based on a comparison of mice which had normal protein FasL activity against mice that were bred to be deficient in this protein.

47.   The study was based on data from Scott-Levin Inc., a health care market research company in Newtown, Pa.

48.   The study was based on questionnaires given to a representative sampling of employees at Du Pont, and on focus groups to supplement that data.

49.   The study was based on reports in research journals and detailed interviews.

50.   Their study was based on detailed measurements of dissolved oxygen in the river and an analysis of differences in oxygen concentrations before and after the mussels appeared.