Gerald H. F. Gardner, who provided the statistical underpinnings for the landmark Supreme Court case that resulted in the prohibition of sex discrimination in newspaper want ads, died Saturday in Pittsburgh. He was 83.

The cause was leukemia, said his wife, Jo Ann Evansgardner.

Dr. Gardner, a geophysicist by profession and a mathematician by training but a social activist by temperament, taught at several universities, including the Carnegie Institute of Technology (now known as Carnegie-Mellon University), Rice University and the University of Houston. He worked for more than two decades for the Gulf Research and Development Company, a subsidiary of Gulf Oil, contributing to significant advances in applied seismology, or methods for finding oil and natural gas deposits.

But Dr. Gardner, a shy man who was uncomfortable in a lecture hall, was most formidable behind the scenes as a social activist, especially on behalf of women’s rights. He and his wife were among the earliest members of First Pittsburgh NOW, itself an early chapter of the National Organization for Women, which was founded in 1966.