Majority of the quantitative research studies that are undertaken by academician and scholars will be one of three types, which we refer to as duplication, generalization or extension.
Duplication research studies take some published research and then repeat it under identical scenario and check if the results obtained are same as in the original research study. In some cases the researcher might just use the original data and reanalyze to check if the original results were accurate. There is very little or no value addition in these sort of studies and hence most of the journal editors will generally not accept replication studies for publication in their journal.
In reality, most of the research studies involve either generalization or extension of some previous research study. Generalization simply means replicating a piece of research to determine whether the findings are generalizable within a different setting/context (such as population, treatment condition etc.). On the other hand, extension involves replicating existing research to take into account new research designs, methods and measurement procedures, and data analysis techniques.
Though you may call them by some other name, and it hardly matter, the important point is that the things you need to think about when doing your dissertation differ somewhat depending the type of your study. It is important to highlight that the these three studies might not be mutually exclusive, which means that your dissertation can incorporate all the three elements or just one of them.