2.1 Principle

The logit transforms the response with the formula log (p / (1-p)) and transforms the dose with a log.

The formula applied in this logit variation takes into account a blank:
Log ((response - blank) / (Bmax - response)) = logit.

The maximum response (Bmax) is when the dose has become infinite.
The responses are logit transformed and the doses with a log.
A linear regression is calculated on the transformed data pairs.
The concentration is calculated with these regression parameters and the calculated Bmax.

Concentration = Exp ((logit (response) - intercept) / slope) * Dilution

If the spline regression option is chosen, straight line segments are drawn between the averages of a response per dose