fit_clutter function

Fit the Clutter model for growth and yield

Fit the Clutter model for growth and yield using the two stage least squares method (2SLS).

fit_clutter(
  df,
  age,
  dh,
  basal_area,
  volume,
  site,
  plot,
  .groups = NA,
  model = "full",
  keep_model = FALSE
)

Arguments

• df: A data frame.
• age: Quoted name for the age variable.
• dh: Quoted name for the dominant height variable.
• basal_area: Quoted name for the basal area variable.
• volume: Quoted name for the volume area variable.
• site: Quoted name for the site variable.
• plot: Quoted name for the plot variable.
• .groups: Optional argument. Quoted name(s) of grouping variables used to fit multiple regressions, one for each level of the provided variable(s). Default NA.
• model: Character variable for the type of the model fitted. If "full", the full model will be used. if "mod", a modified model will be fitted, where the X3 variable is excluded from the regression. Default: full.
• keep_model: If TRUE a variable with the regression model will be kept in the data frame. Default: FALSE.

Returns

A data frame with the regression coefficients.

Examples

library(forestmangr)
data("exfm17")
head(exfm17)

# To fit the Clutter model we just need to define the data, and age, dominant height,
# basal area, volume, site and plot variables:
fit_clutter(exfm17, "age", "DH", "B", "V", "S", "plot")

# To fit the alternate model (without a1) just use model="mod":
fit_clutter(exfm17, "age", "DH", "B", "V", "S", "plot",model="mod")

# To keep the regression model, use keep_model=TRUE:
fit_clutter(exfm17, "age", "DH", "B", "V", "S", "plot", keep_model=TRUE)

References

Clutter, J. L. (1963) Compatible Growth For Loblolly by the Southeastern, Forest Science, 9(3), pp. 354–371. Sullivan, A. D. and Clutter, J. L. (1972) A Simultaneous Growth and Yield for Loblolly Pine, Forest Science, 18(1), pp. 76–86. Campos, J. C. C. and Leite, H. G. (2017) Mensuracao Florestal: Perguntas e Respostas. 5a. Vicosa: UFV.

See Also

other sampling functions: est_clutter for estimating the Clutter growth and yield model variables, and classify_site for classifying data according to site.

Author(s)

Sollano Rabelo Braga sollanorb@gmail.com