Software engineering is the latest and most complicated discipline of engineering. Current software engineering is based on empirical practices, while theoretical research and investigation into foundations of software engineering have long been left behind. Theoretical software engineering studies the nature of software, mathematical models of software architecture, mechanism of software behaviors, methodologies of large scale software development and laws behind software behaviors and software engineering practices. The main part of software development is using a software models to find a systematic and disciplined way of the solutions for a given project. This paper focuses on fundamental theory of different lifecycle models with the cross comparison of statistical calculation for software model analysis with emphasis on the dependency of activities on phases. We used a mechanism for finding the dependency matrices between the different phases of different models. In this paper we devised a methodology for estimating the occurrence relationship between the activities with its correlation and regression. Finally we have given the comparison of statistical calculation for dependency values among different models.