Designing research in the social sciencesMaggetti, M., Gilardi, F. & Radaelli, C. M. (2013). Designing research in the social sciences. London, : SAGE Publications Ltd. doi: 10.4135/9781473957664 (Chapter 4. Pp. 69-92)
Note: Don’t worry if you do not understand the equations in the potential-outcomes framework section of this chapter, just read on to the section that is headed “Experiments” and read through to page 85. This will explain the main types of quantitative research designs. The sections on Discontinuity Designs and Instrumental variables are difficult to follow so again, take from them what you can. The Lessons for Research Design on page 88 is a nice summary.