ABSTRACT
Garfield and Ahlgren (1988) argued that little research has been done on how students come to understand statistical concepts. Mathews and Clark (1997) interviewed eight college students enrolled in an introductory statistics course and found that although all were highly successful in the course, none of the students demonstrated a conceptual understanding of the introductory level material. One area of statistical instruction that has received very little attention is students’ understanding of variability (Reading & Shaughnessy, 2004; Shaughnessy, 1997). This is the case despite the central role the concept plays in statistics (Hoerl & Snee, 2001; Moore, 1990; Snee, 1990) and an apparent conceptual gap in students’ understanding of variability (Shaughnessy, 1997). An understanding of statistical variation is needed to understand advanced concepts such as the nature of sampling distributions, inference, and p-values (Chance, delMas, & Garfield, 2004; delMas, Garfield, & Chance, 1999; Saldahna & Thompson, 2002; Thompson, Saldahna, & Liu, 2004).
