Editing Correlation ratio (section)

==Pearson vs. Fisher==
The correlation ratio was introduced by [[Karl Pearson]] as part of [[analysis of variance]]. [[Ronald Fisher]] commented: 
<blockquote>"As a descriptive statistic the utility of the correlation ratio is extremely limited. It will be noticed that the number of [[Degrees of freedom (statistics)|degrees of freedom]] in the numerator of <math>\eta^2</math> depends on the number of the arrays"<ref>[[Ronald Fisher]] (1926) "[[Statistical Methods for Research Workers]]", {{ISBN|0-05-002170-2}} [http://psychclassics.yorku.ca/Fisher/Methods/chap8.htm (excerpt)]</ref></blockquote> to which [[Egon Pearson]] (Karl's son) responded by saying 
<blockquote>"Again, a long-established method such as the use of the correlation ratio [§45 The "Correlation Ratio" η] is passed over in a few words without adequate description, which is perhaps hardly fair to the student who is given no opportunity of judging its scope for himself."<ref>Pearson E.S. (1926) "Review of Statistical Methods for Research Workers (R. A. Fisher)", "Science Progress", 20, 733-734. [http://www.economics.soton.ac.uk/staff/aldrich/fisherguide/esp.htm#esp1 (excerpt)]</ref></blockquote>

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