linear.linear: Analysis: Linear-Linear

Description

This function performs linear linear regression analysis.

Usage

linear.linear(
  trat,
  resp,
  middle = 1,
  CI = FALSE,
  bootstrap.samples = 1000,
  sig.level = 0.05,
  error = "SE",
  ylab = "Dependent",
  xlab = "Independent",
  theme = theme_classic(),
  point = "all",
  width.bar = NA,
  legend.position = "top",
  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); breakpoint and the graph using ggplot2 with the equation automatically.

Arguments

trat: Numeric vector with dependent variable.
resp: Numeric vector with independent variable.
middle: A scalar in [0,1]. This represents the range that the change-point can occur in. 0 means the change-point must occur at the middle of the range of x-values. 1 means that the change-point can occur anywhere along the range of the x-values.
CI: Whether or not a bootstrap confidence interval should be calculated. Defaults to FALSE because the interval takes a non-trivial amount of time to calculate
bootstrap.samples: The number of bootstrap samples to take when calculating the CI.
sig.level: What significance level to use for the confidence intervals.
error: Error bar (It can be SE - default, SD or FALSE)
ylab: Variable response name (Accepts the expression() function)
xlab: treatments name (Accepts the expression() function)
theme: ggplot2 theme (default is theme_classic())
point: defines whether you want to plot all points ("all") or only the mean ("mean")
width.bar: Bar width
legend.position: legend position (default is "top")
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 SiZer package

Gabriel Danilo Shimizu

Leandro Simoes Azeredo Goncalves

Details

The linear-linear model is defined by: First curve: $$y = \beta_0 + \beta_1 \times x (x < breakpoint)$$

Second curve: $$y = \beta_0 + \beta_1 \times breakpoint + w \times x (x > breakpoint)$$

References

Chiu, G. S., R. Lockhart, and R. Routledge. 2006. Bent-cable regression theory and applications. Journal of the American Statistical Association 101:542-553.

Toms, J. D., and M. L. Lesperance. 2003. Piecewise regression: a tool for identifying ecological thresholds. Ecology 84:2034-2041.

Examples

Run this code

library(AgroReg)
data("granada")
attach(granada)
linear.linear(time,WL)

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