transect.pwr: Power analysis function for transect design

In HiDef-Aerial-Surveying/HiDEF: The HiDEF useful functions package

Power analysis function for transect design

Description

Taking a single set of transects from a HiDef digital aerial survey will compute the statistical power for detecting population change.

Usage

transect.pwr(
  CC,
  Species,
  nseq = NULL,
  t.space,
  kseq = seq(0, -1, by = -0.1),
  nSim = 10000,
  plot = TRUE,
  by.density = FALSE,
  alternative = "two.sided"
)

Arguments

CC	An sf object. The opened cent count shapefile to process
Species	A vector. The vector of species (using the two letter code) that will be tested. E.G., c("S_CX","S_SP","S_RH","S_GN","S_GD","S_CA")
nseq	A vector (optional). The number of transects to test. If NULL then the code will test a halving, a doubling, and 1.5 times the spacing of the original transects.
t.space	Numeric. A value representing the transect spacing in the cent count.
kseq	Numeric sequence. Defaults to seq(0,1,by=0.1). The vector of effect sizes to test (i.e., the statistical power is to be tested).
nSim	Number of simulations to run power analysis on.
plot	Boolean. Whether or not to plot the output in the console. A plot will be returned in the output list.
by.density	Boolean. If TRUE, will use density rather than count
alternative	indicates the alternative hypothesis and must be one of "two.sided" (default), "less", or "greater". You can specify just the initial letter of the value, but the argument name must be given in full. See ‘Details’ of stats::ks.test() for the meanings of the possible values.

Value

A list. Contains plotobj (the plot as a ggplot), powervals (the data frame with power values), and samplesize (the sample sizes as a data frame)

Examples

CentCount <- "D:/Power_Analysis/Data/Zone113_M02_S01_21_Output/Zone113_M02_S01_21_Output-CentCount.shp"
## Read the CentCount and convert to a data frame
CC <- sf::st_read(CentCount)

## Create the sequences of the original population (effect size)
kseq <- seq(0,-1,by=-0.1)
## Create the number of transects to test
nseq <- c(21,43,64,86)
labs <- c("5km","2.5km","1.68km","1.25km")
names(nseq) <- labs
Species <- c("S_CX","S_SP","S_RH","S_GN","S_GD","S_CA")
poweranalysis <- transect.pwr(CC=CC,Species = Species,nseq = nseq,kseq = kseq,t.space = 2.5,nSim = 1000, plot = TRUE, alternative = "less")

HiDef-Aerial-Surveying/HiDEF documentation built on Nov. 21, 2023, 5:54 a.m.