Personal Software Process (PSP) is a process that develops individual skills in software engineers to control and improve the quality of their work practices. This paper presents an evaluative study on the effectiveness of design and code reviews includes into the PSP development activities. The study carried out with students of the Management Information Systems in National University of Colombia - Manizales. An experiment was designed to develop a program using PSP scripts forms standards and measures. The program was developed by two groups of students one group used the revisions and the other did not. Test hypotheses carried out show that there are no significant differences in the effectiveness of PSP code and design revisions compared to traditional development in which no revisions are made. However design and code reviews achieved to eliminate defects in the early stages effectively. This work benefits software engineers to know the effectiveness of design and code reviews from an empirical point of view.