·Rates, Risk Ratio, Odds, Odds Ratio, Log Odds
·Phi Coefficient of Association
·ChiSquare Test of Association
·Fisher Exact Probability Test
For two groups of subjects, each sorted according to the absence or presence of some particular characteristic or condition, this page will calculate standard measures for Rates, Risk Ratio, Odds, Odds Ratio, and Log Odds. It will also
 calculate the Phi coefficient of association;_{T}
 perform a chisquare test of association, if the sample size is not too small; and_{T}
 perform the Fisher exact probability test, if the sample size is not too large. [Although the Fisher test is traditionally used with relatively small samples, the programming for this page will handle fairly large samples, up to about n=1000, depending on how the frequencies are arrayed within the four cells.]_{T}
 For intermediate values of n, the chisquare and Fisher tests will both be performed.
To proceed, enter the values of X
_{0}Y
_{1}, X
_{1}Y
_{1}, etc., into the designated cells. When all four cell values have been entered, click the «Calculate» button. To perform a new analysis with a new set of data, click the «Reset» button.
The logic and computational details of the Chi
Square and Fisher tests are described in Chapter 8 and Subchapter 8a, respectively, of Concepts and Applications. A briefer account of the Fisher test will be found toward the bottom of this page.
Data Entry_{T}
Rate = proportion in group with condition present
Risk Ratio = Rate[1]/Rate[2]
Odds[1] = present[1]/absent[1]
Odds[2] = present[2]/absent[2]
Odds Ratio = Odds[1]/Odds[2]
Log Odds = natural logarithm of Odds Ratio
Fisher Exact Probability Test:_{T}
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©Richard Lowry 2001
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