This thesis compares conceptual data models including extended entity relationship (EER), semantic object model (SOM), object role modeling (ORM), and object modeling technique (OMT) in terms of correctness, time, and perceived ease-of-use. For an empirical study, 28 graduates and 72 undergraduates are selected and then divided into four equally sized groups. Each group is trained with one data modeling technique. Two cases are used; one case is prepared in natural language and the other in enterprise form. Model correctness is measured by the degree of correctness in modeling each case. Time is measured by the required time in modeling each case. Perceived ease-of-use is measured by the use of questionnaires developed by Davis. The study results imply that there are some differences among the four conceptual data modeling techniques. A correlation between natural language case and enterprise form case is found.