Description Usage Arguments Details Value Note Author(s) References
'baro5' allows specification of the baroreflex 5-parameter dose response function, under various constraints on the parameters.
1 2 |
fixed |
numeric vector. Specifies which parameters are fixed and at what value they are fixed. NAs for parameter that are not fixed. |
names |
a vector of character strings giving the names of the parameters (should not contain ":"). The order of the parameters is: b1, b2, c, d, e (see under 'Details'). |
method |
character string indicating the self starter function to use. |
ssfct |
a self starter function to be used. |
The five-parameter function given by the expression
y = c + \frac{d-c}{1+f\exp(b1(\log(x)-\log(e))) + (1-f)\exp(b2(\log(x)-\log(e)))}
f = 1/( 1 + \exp((2b1b2/|b1+b2|)(\log(x)-\log(e))))
If the difference between the parameters b1 and b2 is different from 0 then the function is asymmetric.
The value returned is a list containing the nonlinear model function, the self starter function and the parameter names.
See the example for the dataset heartrate
.
Christian Ritz
Ricketts, J. H. and Head, G. A. (1999) A five-parameter logistic equation for investigating asymmetry of curvature in baroreflex studies. Am. J. Physiol. (Regulatory Integrative Comp. Physiol. 46), 277, 441–454.
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