Inclusion and exclusion criteria are used to set the boundaries for your review.  Usually you will define these after setting the research question and before the search is conducted. Yet, it may be necessary to do some test searches first so you can determine the appropriate boundaries of your project.  You can use many different aspects as criteria for the inclusion and exclusion of studies, such as:

• date of publication
  How far back will you search for information?  You will usually need to motivate why your restrict your search by date.
• location
  Will your study be limited to a setting like hospitals, schools, or small businesses?  Are you interested in a specific geographical area?
• age of participants
  Are you perhaps only interested in research about children or the elderly?
• study design
  Do you want qualitative or quantitative studies or perhaps both? Do you want a specific study type such as randomized controlled trials?
• type of publication
  Do you only want peer-reviewed articles from scholarly journals or are you also interested in publications like conference proceedings or editorials?

You may also need to delineate your working definition of key concepts, e.g., entrepreneurship, participation, sustainability.