Es, except at 40 (Figure 2). The strongly U-shaped curve for random graphics indicates that relative inaccuracy was higher when the graphic depicted low or high percentages. By contrast, for sequential graphics, relative inaccuracy was much smaller, never rising above 0.09. Also, the curve was roughly flat or slightly increasing, suggesting that inaccuracy in estimating sequential purchase BAY 11-7083 graphs was less strongly affected by the percentage depicted. All of the respondents saw the 29 graphic, and about one quarter (n = 43) also saw the 40 graphs. For these respondents, we ascertained whether they correctly ranked the 29 and 40 random graphs, that is, whether they assigned the 29 graphic a lower estimate than the 40 one. Of the 43 subjects, 31 (72 ) correctly ranked the 2 random graphs, 11 (26 ) estimated the 29 proportion to be larger than the 40 one, and 1 person assigned them exactly the same estimate. This suggests that the inaccuracy induced by the random arrangement was sometimes large enough to cause confusion between proportions differing by as many as 11 percentage points. By contrast, with sequential graphics, only 4 people (9 ) wrongly assigned the sequential 29 graph a larger estimate than the sequential 40 one. However, respondents’ estimates of the same quantity in different arrangements were correlated (all r’s greater than 0.43), suggesting that the inaccuracy associated with the random graphic did not eliminate all sense of the size of the proportion. For the random 6 graph, 22 people (13.3 of all respondents) gave “14” as the answer, raising the possibility that they had counted the 14 blue figures (which represented 6 of the 240 figures in the graph). (Nine of these respondents also gave “14” as the ML240 supplement answer for the sequential 6 graph.) No similar pattern was evident for the other graphs. We repeated the analysis of mean inaccuracy and relative inaccuracy omitting these respondents. For the 6 random graph, mean inaccuracy decreased from 2.7 percentage points to 1.9 percentage points but remained statistically significantly different from 0 (P = 0.01); relative inaccuracy decreased from 0.46 to 0.32. For the 6 sequential, mean inaccuracy decreased from 0.5 to 0.03 percentage points, which remained not statistically different from 0 (P = 0.96); relative inaccuracy decreased from 0.03 to 0.005. The proportion whose random estimates were higher than their sequential estimates changed only slightly from 61.2 to 64.3 . Thus, omitting these responses reduced the mean overestimation but did not change conclusions about statistical significance. Our 3rd hypothesis was that numeracy would be associated with accuracy in estimation. Better numeracy was correlated with decreasing inaccuracy for 29 random and sequential (r = -0.26, P = 0.001 for random; r = -0.16, P = 0.04 for sequential) and 6 random (r = -0.17, P = 0.03), but not for the 6 sequential or for 40 , 50 , 60 , or 70 graphics inAuthor Manuscript Author Manuscript Author Manuscript Author ManuscriptMed Decis Making. Author manuscript; available in PMC 2017 June 02.Ancker et al.Pageeither arrangement (all r < |0.15|, all P > 0.10). Low-numeracy respondents gave higher mean estimates for all graphics than high-numeracy ones, and the differences were statistically significant for 6 random (7.7 v. 11.6, P = 0.01), 29 random (38.7 v. 31.5, P = 0.002), and 29 sequential (31.7 v. 25.8, P = 0.005) but not for the 6 sequential or for the 40 , 50 , 60 , or 70 graph.Es, except at 40 (Figure 2). The strongly U-shaped curve for random graphics indicates that relative inaccuracy was higher when the graphic depicted low or high percentages. By contrast, for sequential graphics, relative inaccuracy was much smaller, never rising above 0.09. Also, the curve was roughly flat or slightly increasing, suggesting that inaccuracy in estimating sequential graphs was less strongly affected by the percentage depicted. All of the respondents saw the 29 graphic, and about one quarter (n = 43) also saw the 40 graphs. For these respondents, we ascertained whether they correctly ranked the 29 and 40 random graphs, that is, whether they assigned the 29 graphic a lower estimate than the 40 one. Of the 43 subjects, 31 (72 ) correctly ranked the 2 random graphs, 11 (26 ) estimated the 29 proportion to be larger than the 40 one, and 1 person assigned them exactly the same estimate. This suggests that the inaccuracy induced by the random arrangement was sometimes large enough to cause confusion between proportions differing by as many as 11 percentage points. By contrast, with sequential graphics, only 4 people (9 ) wrongly assigned the sequential 29 graph a larger estimate than the sequential 40 one. However, respondents’ estimates of the same quantity in different arrangements were correlated (all r’s greater than 0.43), suggesting that the inaccuracy associated with the random graphic did not eliminate all sense of the size of the proportion. For the random 6 graph, 22 people (13.3 of all respondents) gave “14” as the answer, raising the possibility that they had counted the 14 blue figures (which represented 6 of the 240 figures in the graph). (Nine of these respondents also gave “14” as the answer for the sequential 6 graph.) No similar pattern was evident for the other graphs. We repeated the analysis of mean inaccuracy and relative inaccuracy omitting these respondents. For the 6 random graph, mean inaccuracy decreased from 2.7 percentage points to 1.9 percentage points but remained statistically significantly different from 0 (P = 0.01); relative inaccuracy decreased from 0.46 to 0.32. For the 6 sequential, mean inaccuracy decreased from 0.5 to 0.03 percentage points, which remained not statistically different from 0 (P = 0.96); relative inaccuracy decreased from 0.03 to 0.005. The proportion whose random estimates were higher than their sequential estimates changed only slightly from 61.2 to 64.3 . Thus, omitting these responses reduced the mean overestimation but did not change conclusions about statistical significance. Our 3rd hypothesis was that numeracy would be associated with accuracy in estimation. Better numeracy was correlated with decreasing inaccuracy for 29 random and sequential (r = -0.26, P = 0.001 for random; r = -0.16, P = 0.04 for sequential) and 6 random (r = -0.17, P = 0.03), but not for the 6 sequential or for 40 , 50 , 60 , or 70 graphics inAuthor Manuscript Author Manuscript Author Manuscript Author ManuscriptMed Decis Making. Author manuscript; available in PMC 2017 June 02.Ancker et al.Pageeither arrangement (all r < |0.15|, all P > 0.10). Low-numeracy respondents gave higher mean estimates for all graphics than high-numeracy ones, and the differences were statistically significant for 6 random (7.7 v. 11.6, P = 0.01), 29 random (38.7 v. 31.5, P = 0.002), and 29 sequential (31.7 v. 25.8, P = 0.005) but not for the 6 sequential or for the 40 , 50 , 60 , or 70 graph.