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A significance value (P-value) and 95% Confidence Interval (CI) of the observed mean is reported. This procedure calculates the difference of an observed mean with a hypothesized value.

Test mean is equal to: enter the value to compare the mean to.

The observed sample mean, standard deviation and sample size (n).

(Version 22.The Test for one mean can be used to test the hypothesis that a sample mean is equal to a given mean (with unknown standard deviation) or certified value.

Sahai H, Khurshid A (1996) Statistics in epidemiology: methods, techniques, and applications.

Hanley H (1986) Analysis of Crude Data.

The P-value is the exact mid-P double sided P-value (Hanley, 1986). The P-value is obtained using the Chi 2-statistic.įor 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). Computational detailsįor 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). If the P-value is less than 0.05 it can be concluded that the ratio R1/R2 is significantly different from 1 (which is the case when the rates are equal).

The ratio of the two rates (the incidence rate ratio) R1/R2 with its 95% Confidence Interval and associated P-value.

If the P-value is less than 0.05 it can be concluded that there is a statistical significant difference between the two rates.

The difference between the two rates R2-R1 with its 95% Confidence Interval and associated P-value.

The (incidence) rate in the two groups with their Poisson 95% Confidence Interval.

the rate 10/200 equals 0.05 and can be represented as 1:20.

Option Express result as 1:X: when this option is selected the rate R will be displayed as 1:(1/R), e.g.

Denominator: for example the total person-years for each group.

Numerator: the observed number of events in each group.

This form allows to compare the rates in two groups. 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.

Download the new version for ipod MedCalc 22.007