Longitudinal development of inferential reasoning by school students

This study follows an earlier study of school students' abilities to draw inferences when comparing two data sets presented in graphical form (Watson and Moritz, 1999). Forty-two students who were originally interviewed in grades 3 to 9, were subsequently interviewed either three or four years later. The results for individual student development add to the credibility of the cross-age observations, as well as support the hierarchical framework suggested by the original study. Changes in levels of performance and strategies for drawing conclusions are documented. A further step from the original study is the consideration of how students used the variation displayed in the graphical presentation of the data sets as a basis for decision-making. Implications for teaching and for further research are discussed.