VB: Analysis: Von Bertalanffy

In AgroReg: Regression Analysis Linear and Nonlinear for Agriculture

Analysis: Von Bertalanffy

Description

The Von Bertalanffy model. It's a kind of growth curve for a time series and takes its name from its creator, Ludwig von Bertalanffy. It is a special case of the generalized logistic function. The growth curve (biology) is used to model the average length from age in animals.

Usage

VB(
  trat,
  resp,
  initial = NA,
  sample.curve = 1000,
  ylab = "Dependent",
  xlab = "Independent",
  theme = theme_classic(),
  legend.position = "top",
  r2 = "all",
  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,
  yname.formula = "y",
  xname.formula = "x",
  comment = NA,
  fontfamily = "sans",
  print.on = TRUE
)

Arguments

trat	Numeric vector with dependent variable.
resp	Numeric vector with independent variable.
initial	Starting estimates
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)
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
yname.formula	Name of y in the equation
xname.formula	Name of x in the equation
comment	Add text after equation
fontfamily	Font family
print.on	Print output

Details

The model function for the von Bertalanffy model is:

y = L(1-exp(-k(t-t0)))

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)

Gabriel Danilo Shimizu

Leandro Simoes Azeredo Goncalves

Examples

library(AgroReg)
x=seq(1,20)
y=c(0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 0.91,
    0.92, 0.94, 0.96, 0.98, 1.00, 1.00, 1.00, 1.00, 1.00, 1.00)
VB(x,y)

AgroReg documentation built on July 2, 2025, 1:08 a.m.