Triangulating Your Evidence
Triangulation: multiple forms of overlapping, diverse pieces of evidence and perspectives.
Triangulation is a key tenant of the anthropological approach to data gathering (and therefore, teacher research). One should gather a wide variety of evidence for the purposes of triangulation (Jacob, 1990; O'Malley & Valdez Pierce, 1996; Wiggins, 1998).
As opposed to relying on one single form of evidence or perspective as the basis for findings, multiple forms of diverse and redundant types of evidence are used to check the validity and reliability of the findings (Jacob, 1990; O'Malley & Valdez Pierce, 1996; Maxwell, 1996; Wiggins, 1998). Over-relying on any one form of evidence may impact validity of the findings.
By using multiple forms of evidence and perspectives, a truer portrait of the student can be developed (Wiggins, 1998). While the same biases in evidence collection still come into play, because more types of evidence are being used to form one's opinion about the student, there are more cross checks on the accuracy of the decision.
References
Jacob, E. (1990). Alternative Approaches for Studying Naturally Occurring Human Behavior and Thought in Special Education Research. The Journal of Special Education, 24,(2), 195-211.
Maxwell, J. (1996). Using Qualitative Research to Develop Causal Explanations. Harvard University: Harvard Project on Schooling and Children.
O'Malley, J.M. & Valdez Pierce, L. (1996). Authentic Assessment for English Language Learners: Practical Approaches for Teachers. Reading, MA: Addison-Wesley Publishing Company.
Wiggins, G. (1998). Educative Assessment. San Francisco, CA: Jossey-Bass.