baro5 {drc}R Documentation

The modified baro5 function

Description

'baro5' allows specification of the baroreflex 5-parameter dose response function, under various constraints on the parameters.

Usage

baro5(lowerc = c(-Inf, -Inf, -Inf, -Inf, -Inf), 
upperc = c(Inf, Inf, Inf, Inf, Inf), fixed = c(NA, NA, NA, NA, NA), 
names = c("b1", "b2", "c", "d", "e"), scaleDose = TRUE, useDer = FALSE)

Arguments

lowerc numeric vector. The lower bound on parameters. Default is minus infinity.
upperc numeric vector. The upper bound on parameters. Default is plus infinity.
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 default is reasonable (see under 'Usage'). The order of the parameters is: b1, b2, c, d, e (see under 'Details').
scaleDose logical. If TRUE dose values are scaled around 1 during estimation; this is required for datasets where all dose values are small.
useDer logical. If TRUE derivatives are supplied, otherwise they are not supplied. Not implemented.

Details

The five-parameter function given by the expression

y = c + frac{d-c}{1+fexp(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.

Value

The value returned by the 'baro5' is a list with the following components

fct The dose response function.
ssfct The self starter function.
deriv1 The first derivative. Not available.
deriv2 The second derivative. Not available.
lowerc The lower bounds on the parameters.
upperc The upper bounds on the parameters.
edfct The ED function. Not available.
sifct The SI function. Not available.

Author(s)

Christian Ritz

References

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.

Examples


## See the example for the heartrate dataset


[Package drc version 1.6-1 Index]