Professor Dr. Robert Cavanagh
Curtin University, Western Australia

Title: Let Me Count The Reasons Why I Use Rasch Measurement Theory

Abstract:

My path to Rasch Measurement has been influenced by a desire to understand the nature of science and scientific research. I obtained post-graduate qualifications in Science Education; was a Science educator - teacher, Senior Master of Physical Science, and curriculum developer; and subsequently applied scientific approaches in doctoral and post-doctoral research into learning environments. However, I had concerns about using scientific approaches to understand educational phenomena due to the risk of de-emphasising their humanist nature. My understanding of the role of measurement in the human sciences was a major contributor to this perceived tension. In particular the a prioriassumptions made about the construct of interest and how these influence the choice of measurement paradigm. Since introduction to Rasch Measurement Theory, I now believe representing the humanist element in educational phenomena requires a stochastic view which acknowledges an element of randomness and necessitates measures that communicate probability of actions, dispositions or ability. However, this requirement does not negate the need for human science measures to perform without bias and for the scale to be independent of the persons measured, for the measure to be invariant or to display objectivity. A related attribute of human science measures is that the steps in person and item calibrations need to be equal akin to the intervals in natural science instrument scales. All the preceding requirements are satisfied by Rasch Measurement Theory. I will argue for the confluence of modern paradigms of science, measurement, human science and human measurement. Specifically, that there is symbiosis between our conceptualisation of human science and of the measures we use for its representation.