The positive and negative effects of separating the chairman of the board and CEO roles on organizations

This is a corporate government issue. Separating the roles of the chairman of the board and CEO is a key point of corporate governance in today's business world. Not only in family businesses, but even in large corporations, still sometimes the two roles are combined in one person. In this case there is no segregation of duties and it's like the chairman monitors himself as a CEO. Need to investigate why companies still do that in different types including family businesses and corporates. What are the positive and negative effects of separating the two roles on the organization? The hypothesis should be: Separating the role sof chairman and CEO has positive effects on organizations. Should have an abstract, introduction, literature review that leads to developing that hypotheiss and then a conclusion part without empirical results in between.