“…(Heinicke, 2012;Sere et al, 2001) Similarly, when asked whether two data sets with different means but overlapping spreads agree with each other or not, many of these students ignore data scatter and just use the arithmetic means (Abbott, 2003;Allie et al, 1998;Cauzinille-Marmeche et al, 1985;Davidowitz et al, 2001;Deardorff, 2001;Ibrahim, 2006;Leach et al, 1998;Lubben et al, 2001;Pillay et al, 2008;Rollnick et al, 2001;Sere et al, 2001Sere et al, , 1993 or individual data points. (Allie et al, 1998;Buffler et al, 2001;Davidowitz et al, 2001;Deardorff, 2001;Heinicke, 2012;Ibrahim, 2006;Rollnick et al, 2001;Sere et al, 2001;Volkwyn et al, 2008) This suggests that the correct answer on the original question with identical means may have come about for some reason other than deep conceptual understanding about spread. Students who do consider data spread in deciding whether two sets of data agree with each other or not will often say that the data agrees if the size of the spread is the same whether there is overlap or not.…”