BC: Analysis: Brain-Cousens

In AgroReg: Regression Analysis Linear and Nonlinear for Agriculture

Analysis: Brain-Cousens

Description

The 'BC.4' and 'BC.5' logistical models provide Brain-Cousens' modified logistical models to describe u-shaped hormesis. This model was extracted from the 'drc' package.

Usage

BC(
  trat,
  resp,
  npar = "BC.4",
  sample.curve = 1000,
  ylab = "Dependent",
  xlab = "Independent",
  theme = theme_classic(),
  legend.position = "top",
  r2 = "all",
  ic = FALSE,
  fill.ic = "gray70",
  alpha.ic = 0.5,
  error = "SE",
  point = "all",
  width.bar = NA,
  scale = "none",
  textsize = 12,
  pointsize = 4.5,
  linesize = 0.8,
  linetype = 1,
  pointshape = 21,
  fillshape = "gray",
  colorline = "black",
  round = NA,
  xname.formula = "x",
  yname.formula = "y",
  comment = NA,
  fontfamily = "sans"
)

Arguments

trat	Numeric vector with dependent variable.
resp	Numeric vector with independent variable.
npar	Number of model parameters (default is BC.4)
sample.curve	Provide the number of observations to simulate curvature (default is 1000)
ylab	Variable response name (Accepts the expression() function)
xlab	Treatments name (Accepts the expression() function)
theme	ggplot2 theme (default is theme_bw())
legend.position	Legend position (default is "top")
r2	Coefficient of determination of the mean or all values (default is all)
ic	Add interval of confidence
fill.ic	Color interval of confidence
alpha.ic	confidence interval transparency level
error	Error bar (It can be SE - default, SD or FALSE)
point	Defines whether you want to plot all points ("all") or only the mean ("mean")
width.bar	Bar width
scale	Sets x scale (default is none, can be "log")
textsize	Font size
pointsize	Shape size
linesize	Line size
linetype	line type
pointshape	Format point (default is 21)
fillshape	Fill shape
colorline	Color lines
round	round equation
xname.formula	Name of x in the equation
yname.formula	Name of y in the equation
comment	Add text after equation
fontfamily	Font family

Details

The model function for the Brain-Cousens model (Brain and Cousens, 1989) is

y = c + \frac{d-c+fx}{1+\exp(b(\log(x)-\log(e)))}

and it is a five-parameter model, obtained by extending the four-parameter log-logistic model (LL.4 to take into account inverse u-shaped hormesis effects. Fixing the lower limit at 0 yields the four-parameter model

y = 0 + \frac{d-0+fx}{1+\exp(b(\log(x)-\log(e)))}

used by van Ewijk and Hoekstra (1993).

Value

The function returns a list containing the coefficients and their respective values of p; statistical parameters such as AIC, BIC, pseudo-R2, RMSE (root mean square error); largest and smallest estimated value and the graph using ggplot2 with the equation automatically.

Author(s)

Model imported from the drc package (Ritz et al., 2016)

Gabriel Danilo Shimizu

Leandro Simoes Azeredo Goncalves

References

Seber, G. A. F. and Wild, C. J (1989) Nonlinear Regression, New York: Wiley & Sons (p. 330).

Ritz, C.; Strebig, J.C. and Ritz, M.C. Package ‘drc’. Creative Commons: Mountain View, CA, USA, 2016.

See Also

LL, CD,GP

Examples

library(AgroReg)
data("aristolochia")
attach(aristolochia)
BC(trat,resp)

AgroReg documentation built on May 29, 2024, 9:13 a.m.