When should you execute Fisher exact test, not chi-square test?

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You should not execute chi-square test but Fisher exact probability test when gland total of cross tabulation was smaller than 20 or one or greater than one cells had smaller than 5 expected value. In this article, I would like to describe how to solve expected value. Expected value is calculated with marginal total.

We have cross tabulation below;

  TRUE FALSE Marginal total
POSITIVE a b a + b
NEGATIVE c d c + d
Marginal total a + c b + d N 

Expected value of each cells is below;

  TRUE FALSE Marginal total
POSITIVE (a + b)*(a + c)/N (a + b)*(b + d)/N a + b
NEGATIVE (c + d)*(a + c)/N (c + d)*(b + d)/N c + d
Marginal total a + c b + d N 

How to calculate Fisher’s exact test with logarithm?

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投稿者: admin

趣味:写真撮影とデータベース. カメラ:TOYO FIELD, Hasselblad 500C/M, Leica M6. SQL Server 2008 R2, MySQL, Microsoft Access.

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