Dynamic quality control in agile methodology for improving the quality

The advantages of software development using Agile methodology is a well researched and documented topic. However, testing in agile software methodologies is not as well researched. The four values and twelve principles of the Agile Manifesto say nothing concrete about testing or quality assurance. An agile approach such as Scrum also doesn't talk much about Quality Assurance. It's already proven that agile processes produce software fast, but does the software produced adhere to quality? Can we, in some way, improve the quality in agile methodology by focusing on Dynamic Quality Control? There is no notable evidence in existing literature that testing in agile methodologies improve the quality of software compared to other methodologies. We chose a real world project and employed three teams to work on the same project following three different methodologies (Waterfall, Agile and Agile with Dynamic Quality Control) and collected data to compare the effectiveness of testing in each methodology in real world project scenario. We concentrated on five metrics (Defect count, Test coverage, Team maturity, Resource utilization and Lean) to study and compare the change in quality of software when using different methodologies.