Multi-Method Triangulation in a Qualitative Study on Teachers' Practical Knowledge: An Attempt to Increase Internal Validity

This article describes multi-method triangulation as a means to enhance the internal validity in a qualitative study on language teachers' practical knowledge. Teachers' practical knowledge is viewed as a multi-dimensional concept, requiring multiple instruments for its exploration. In the triangulation procedure, data collected with three instruments were analysed and related to each other. Three steps of analysis, preceded by a pre-analysis step, were used to combine these data. The triangulation procedure culminated in a fairly comprehensive understanding of teachers' practical knowledge with respect to the teaching of reading comprehension to 16- to 18-year-old students. It was concluded that multi-method triangulation is a worthwhile procedure to enhance the internal validity in qualitative studies on a complex topic such as teachers' practical knowledge.