Frequently the behaviour of an information system is functionally correct, but it does not meet some quality criteria, such as completeness, consistency, and usability. One way to enhance the capability of an information system is to consider its conceptual model quality as well as its functional behaviour. Conceptual model quality can be defined as a set of perceivable characteristics expressed with quantifiable parameters. The aim of this empirical investigation is to evaluate the quality of different potential conceptual models of the same universe of discourse by different Information Systems (IS) stakeholders. This paper describes: a) a set of quality factors (clarity, simplicity, expressiveness, minimality) applied to different versions of entity-relationship (ER) conceptual schemas, b) an approach enabling a comprehensive comparison of the conceptual schemas, c) an experimentation leading to the evaluation of the same schemas by IS stakeholders such as designers, end-users, and students, based on a sample of about 120 observations using different statistical methods. First results indicate that there exists a strong independence between the IS stakeholders and the quality factors used. A second result reveals a significant difference between groups of respondents in their ways to perceive conceptual schemaspsila quality. Based on our experiment, we are able to identify quality factors relevant to different groups of stakeholders, depending on several dimensions, such as their professional experience, and/or their specialization degree.