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. 2013 Oct 4;5:59. doi: 10.3389/fnagi.2013.00059

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Copyright © Grassi and Borella.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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Statistical artifact when correlating sensation and cognition by including the extremes of the age continuum. The graph depicts two hypothetical age groups of subjects characterized by, respectively, poor sensory and poor cognitive performance (old) and good sensory and good cognitive performance (young). In the data represented, the correlation between sensory and cognitive performance (blue circles) is null within both groups: respectively r(old) = 0.004 and r(young) = -0.062. In contrast, regarding the correlation between sensory and cognitive performance calculated including all participants (red circle), the correlation is strong: r(all) = 0.719. The same artifact affects regression analysis.