The results of two experiments are reviewed in which users' performance in developing query solutions using relational algebra, relational tuple calculus, and relational domain calculus was measured. Sample query solutions in domain and tuple calculus are analysed and compared for complexity. In terms of human factors, tuple calculus is apparently the weakest of the three languages, with domain calculus showing a decided improvement over tuple calculus. Query solution analysis indicates possible reasons for this result. Although users performed best in relational algebra, their performance in domain calculus was equal to that of relational algebra in three of four query classifications. Further investigation is needed to compare algebra and domain calculus in other query classifications, in order to more precisely determine their relative utility in solving complex queries.