Exponential decay model with or without a nonzero lower limit.
meEXD.2(x, d, e) meEXD.3(x, c, d, e)
| x | numeric dose vector |
|---|---|
| d | upper limit |
| e | steepness |
| c | lower limit |
The exponential decay model is a three-parameter model with mean function: $$f(x) = c + (d-c)(\exp(-x/e))$$ The parameter init is the upper limit (attained at \(x=0\)), the parameter plateau is the lower limit reached for x going to infinity and the parameter \(e>0\) is determining the steepness of the decay. The curve is monotonously decreasing in \(x\).
Organisation for Economic Co-operation and Development (OECD) (2006) Current approaches in the statistical analysis of ecotoxicity data: A guidance to application - annexes, Paris: OECD (p. 80).