logistic: Analysis: Logistic

Description

Logistic models with three (L.3), four (L.4) or five (L.5) continuous data parameters. This model was extracted from the drc package.

Usage

logistic(
  trat,
  resp,
  npar = "L.3",
  sample.curve = 1000,
  ylab = "Dependent",
  xlab = "Independent",
  theme = theme_classic(),
  legend.position = "top",
  error = "SE",
  r2 = "all",
  ic = FALSE,
  fill.ic = "gray70",
  alpha.ic = 0.5,
  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"
)

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.

Arguments

trat: Numeric vector with dependent variable.
resp: Numeric vector with independent variable.
npar: Number of model parameters
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")
error: Error bar (It can be SE - default, SD or FALSE)
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
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

Author

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

Gabriel Danilo Shimizu

Leandro Simoes Azeredo Goncalves

Details

The three-parameter logistic function with lower limit 0 is $$y = 0 + \frac{d}{1+\exp(b(x-e))}$$ The four-parameter logistic function is given by the expression $$y = c + \frac{d-c}{1+\exp(b(x-e))}$$ The five-parameter logistic function is given by the expression $$y = c + \frac{d-c}{1+\exp(b(x-e))^f}$$ The function is symmetric about the inflection point (e).

References

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

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

Examples

Run this code

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

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