nelder: Create a Nelder Fan experimental design

In kevinwolz/sysdesign: An R Toolbox for Creating & Analyzing Systematic Experimental Designs in Biology

Description

Creates a Nelder Fan experimental design.

Usage

nelder(
  DN,
  D1,
  N,
  tau = 1,
  even = FALSE,
  max.angle = 360,
  arc.borders = 1,
  spoke.borders = 1
)

Arguments

DN	Plant density within the last experimental arc (plants ha-1) (i.e. lower extreme of experimental plant density range).
D1	Plant density within the first experimental arc (plants ha-1) (i.e. upper extreme of experimental plant density range).
N	Number of experimental arcs (i.e. number of densities to be tested within D1 to DN).
tau	The "rectangularity" proportion. "Rectangularity" is the proportional relationship between the arc length between spokes and the radial length between arcs, where the numerator represents the arc length and the denominator represents radial distance. This proportion has been referred to as "rectangularity" in the historical literature and it remains constant throughout the design. Given that the inner and outer borders of the growing space shape surrounding a plant in a Nelder design are arcs, and that the shape is not truly rectangular or trapezoidal in nature, the term "rectangularity" can be confusing.
even	Logical indicated whether or not the design should be adjusted so that the angle between spokes goes evenly into max.angle (i.e. so that there are no spokes that must be removed from the experiment as border spokes).
max.angle	The maximum rotation (in degrees) of the design. If 360, then a full circle design will be created.
arc.borders	Number of border arcs on either extreme.
spoke.borders	Number of border spokes on either extreme (only used if max.angle < 360).

Details

The Nelder Fan or Nelder Wheel experimental design (Nelder 1962) is an experimental design that systematically varies plant desnity within a single plot. This function creates Nelder Fan Type Ia (Nelder 1962), where the growing area around each plant has a constant shape throughout the design but increases as radius increases. The terminology and calculations used here follow Parrott, Brinks, and Lhotka (2012).

Value

An object of class sysd and class nelder. This is a list of 3 elements:

• "plants" - A data frame (tibble) containing one row for each for each plant in the design.

• "plot" - A data frame (tibble) containing plot charateristics.

• "even.optim" - If even = TRUE, a data frame (tibble) comparing plot characteristics between the scenario where theta is even throughout the design and the scenario where theta is uneven. If even = FALSE, then FALSE.

Author(s)

Kevin J Wolz, [e-mail]

References

• Nelder JA (1962) New kinds of systematic designs for spacing experiments. Biometrics 18:283-307. http://www.jstor.org/stable/2527473

• Parrott DL, Brinks JS, Lhotka JM (2011) Designing Nelder wheel plots for tree density experiments. New Forests 43:245–254. http://link.springer.com/10.1007/s11056-011-9278-4

See Also

Other definition functions: goelz_add_border(), goelz_corners(), goelz_guides(), goelz_mirror(), goelz_optim(), goelz_starts(), goelz(), nelder_biculture_competition(), nelder_biculture_optim(), nelder_biculture(), nelder_decision(), nelder_interspoke_distance(), select_optimal_goelz(), select_optimal_nelder_biculture()

Examples

dat <- nelder(DN         = 1000,
               D1         = 3000,
               N          = 5,
               tau        = 1,
               even       = TRUE,
               max.angle  = 360)

kevinwolz/sysdesign documentation built on June 13, 2020, 1:35 a.m.