There are programs where the Sc.D. and Ph.D. have different degree requirements, though the two degrees are officially considered equivalent. The Engineering school at Washington University in St. Louis, for example, requires four more graduate courses, which can be completed in one year in conjunction with research duties, in the D.Sc. program than the Ph.D. degree, while the Ph.D requires teaching assistance services. The Johns Hopkins University also offers both Ph.D. and Sc.D. in certain programs, with only minor differences in university administration of the degrees. In some institutions, the Sc.D. has been converted to the Ph.D. For instance, the doctoral degree in biostatistics at Harvard recently converted from Sc.D. to Ph.D., even though the doctoral degree structure and requirements have remained identical.