Relative Potency

1) Fit parallel model to reference standard and test sample pair:

Log (RP) = ()

2)Back-transform using the same log base as was used for the dose:
RP = 2 ^{Log 2 (RP)}
RP = e ^{Log e (RP)}
RP = 10 ^{Log10 (RP)}

Confidence interval for relative potency

The variance, s² , of the estimate of Log (RP) is calculated from the variances and covariance of the model parameter estimates

and

using the Delta method. The 95% confidence interval for Log (RP) can then be calculated as:

Log (RP) ± t_{(n- 6, 0.975)} √ s²

where t_{(n- 6, 0.975)} is the 97.5% percentile of the t-distribution with n degrees of freedom; n is the total number of data points in the Test and Reference samples.

The 95% confidence interval for RP is obtained by back-transforming the interval for Log RP using the same log base as was used for the dose.