Data warehouse is an important component of decision support systems, because it provides data of interest for analysis and decision support purposes. This data of interest is useful for analysis due to the multidimensional nature of Star model. Designing a Star model requires ample amount of time, experience, expertise and adequate knowledge of data warehouse designing steps. As an alternative to data warehouse designing steps, transformation techniques are proposed in literature. These techniques transform entity-relationship (ER) model (of online transaction process systems) to Star model. In this study, we present and evaluate a systematic approach for transformation of ER model to Star model. We prove that by using our approach, inexperienced designers can produce star models identical to the star models produced by experienced data warehouse designers. Also, we prove that the Star model produced by existing approaches is different from the Star model produced by our transformation approach. Copyright © 2015 Inderscience Enterprises Ltd.