subject of my research

hi everyone! Here is my idea about my dissertation - I want to analyze how the joining of Baltic countries, which were part of former soviet union, to the Schengen zone reflected on numbers of visitors coming to this countries both from EU and other former members of Soviet Union. I haven't decided yet what methods and approaches I will use for my research, so if anyone have done something similar to this in past, advices and recommendations always welcome! Thanks!