english: For more on research design in the social sciences, see King, Keohane, and Verba (1994), Singleton and Straits (2009), and Khan and Fisher (2013).
non_english: Alang sa dugang sa disenyo sa panukiduki sa social sciences, tan-awa ang King, Keohane, and Verba (1994) , Singleton and Straits (2009) , ug Khan and Fisher (2013) .