What are the most effective strategies for managing quality control on qualitative methods in program evaluation? Why are they the most effective?

Program evaluation can be difficult when there are various stakeholders involved with varying opinions as to what they what to gain from the evaluation process.  Qualitative research allows
us to look at the information on a deeper level.  However, this type of evaluation needs to be mindful that it does not include researcher bias.  As reported by Royse, Thyer, and Padgett (2016), during data collection and analysis, the researcher must resist the inevitable temptation to let personal bias or outside pressure influence.  With any evaluation reliability, validity, and credibility are extremely important.  In order to maintain ethical results one of the most effective ways to manage quality control on qualitative methods would be the use of triangulation.  Triangulation uses multiple methods to ensure credibility and validity of the data being collected.  As reported by Crump and Logan (2016), triangulation is achieved by intentionally using more than one method of gathering and analyzing data about the same phenomenon in order to seek convergence and corroboration and to eliminate the inherent biases from using only one method.  By using triangulation the evaluator can assure that their data includes what the key stakeholders were seeking to find without any bias.  
Crump, B., & Logan, K. (2008). A Framework for Mixed Stakeholders and Mixed Methods. Electronic Journal Of Business Research Methods, 6(1), 21-28.
Royse, D., Thyer, B. A., & Padgett, D. K. (2016). Program evaluation: An Introduction (6th ed.). Boston, MA: Cengage Learning. ISBN-13: 9781305101968