R: The modified baro5 function

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(fixed = c(NA, NA, NA, NA, NA), names = c("b1", "b2", "c", "d", "e"),
      method = c("1", "2", "3", "4"), ssfct = NULL)

### Arguments

`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.

### Details

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.

### Value

The value returned is a list containing the nonlinear model function, the self starter function and the parameter names.

### Note

See the example for the dataset `heartrate`.

### 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.

[Package drc version 3.0-1 Index]