“…Grades for project (Baheti et al, 2002) Functional test cases of the modified programs (Canfora et al, 2003;2006) Number of cases passed (Stotts et al, 2003) Number of defects (Favela et al, 2004), (Zacharis, 2011) Experts evaluate the quality (3 programs) [scale 1-4] (Bravo et al, 2013), (Duque & Bravo, 2008) Number of compilation errors (Bravo et al, 2013), (Duque & Bravo, 2008) Questionnaire (perceived quality of code) (Canfora et al, 2003;2006) Task completion quality (Qiao & Bai, 2017) Questionnaire, survey (perceived quality of code) (Favela et al, 2004) used most often for code productivity is the amount of time spent on completing the tasks (8 studies). Regarding the amount of time spent by DPP pairs and solo programmers on tasks/projects, the various studies found that: there were mixed results (Canfora et al, 2003;2006;Ghorashi & Jensen, 2017); no differences were reported (Hanks, 2008;Qiao & Bai, 2017); less time was spent by DPP pairs; and more time was spent by DPP pairs (Al-Jarrah & Pontelli, 2016).…”