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Comparison of two rates

  1st group 2nd group
Numerator (e.g. number of events counted): 
Denominator (e.g. total person-years): 
Express result as 1:X


A rate is a ratio between a count and another measurement, for example the ratio of a number of events observed and the total number of person-years of observation.

This form allows to compare the rates in two groups.

Required input


MedCalc reports:

Computational details

For the confidence interval of the difference between two rates, MedCalc uses the "Test based Method" given on page 169 of Sahai H, Khurshid A (1996). The P-value is obtained using the Chi2-statistic.

For the confidence interval of the incidence rate ratio, MedCalc uses the "Exact Poisson Method" given on page 172-174 of Sahai H, Khurshid A (1996). The P-value is the exact mid-P double sided P-value (Hanley, 1986).


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