An important step in a dissertation is the theoretical basis that might help explain and shed light on why the problem is happening. For example, if we want to know how different groups responded to the implementation of a new teaching strategy in higher education, you might consider theories related to adult learning. 
Discuss the theoretical framework you think helps explains your topic and problem you will address in your dissertation. Remember, this will also be cited in the literature as well, so make sure to include scholarly resources from a peer reviewed journal.