The following methods and formulas are used for testing the ratio between the test mean and the reference mean using the log transformation.

The difference (*D*) the standard error of the difference (SE) and the confidence interval (CI) are calculated as described for Test mean - reference mean. However, the calculations are performed using the natural log of the data values and the natural log of the equivalence limits.

The ratio, *ρ*, is calculated by converting the difference, *D*, back into the original units as follows:

T-values and p-values are calculated as described for Test mean - reference mean. However, the calculations are performed using the natural log of the data values and the natural log of the equivalence limits.