A recent study was performed that concluded that playing violent video games causes teenagers to exhibit poor behavior outside of school and calls for the ban of all violent video games. The study was conducted using a secondary data set of 10,000 children in high school collected during one week in the spring of 2010. The data set included a large number of variables. The researchers compared the behavior of children who played violent video games with the behavior of those who did not play violent video games. Explain why the researchers most likely conducted a non-experimental design instead of a quasi-experimental design. In your answer describe the key differences between the two research designs.