BC {AgroReg} | R Documentation |

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.

```
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"
)
```

`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 |

`xlab` |
Treatments name (Accepts the |

`theme` |
ggplot2 theme ( |

`legend.position` |
Legend position ( |

`r2` |
Coefficient of determination of the mean or all values ( |

`ic` |
Add interval of confidence |

`fill.ic` |
Color interval of confidence |

`alpha.ic` |
confidence interval transparency level |

`error` |
Error bar (It can be SE - |

`point` |
Defines whether you want to plot all points ("all") or only the mean ("mean") |

`width.bar` |
Bar width |

`scale` |
Sets x scale ( |

`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 |

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).

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.

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

Gabriel Danilo Shimizu

Leandro Simoes Azeredo Goncalves

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.

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

[Package *AgroReg* version 1.2.9 Index]