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Figure 3 These box and whisker plots demonstrate the impact that distance of the catheter from the center of the array has on the cross correlation between virtual and contact atrial electrograms (top), timing error between the two atrial electrograms (middle), and the root mean square (RMS) amplitude of the virtual electrogram (bottom) during sinus rhythm. The box represents the interquartile range and the thick line represents the median value. The whiskers depict the 5th and 95th percentiles. A Mann-Whitney U test was performed to test whether there was a significant difference between points <40 mm and >40 mm from the center of the array. Deterioration was found in both the correlation and timing difference the further the catheter was from the center of the array. However, the amplitude of the virtual electrogram also was reduced the further the catheter was away from the array.