sps (version 0.7.0)

sps_repweights: Bootstrap replicate weights for sequential Poisson sampling

Description

Produce bootstrap replicate weights that are appropriate for Poisson sampling, and therefore approximately correct for sequential Poisson sampling.

Usage

sps_repweights(w, replicates = 1000L, tau = min_tau(1e-04), dist = NULL)
min_tau(tol)

Value

sps_repweights() returns a matrix of bootstrap replicate weights with replicates columns (one for each replicate) and length(w) rows (one for each unit in the sample), with the value of tau as an attribute.

min_tau() returns a function that takes a vector of bootstrap adjustments and returns the smallest value for \(\tau\) such that the rescaled adjustments are greater than or equal to tol.

Arguments

w

[numeric >= 1] A numeric vector of design (inverse probability) weights for a (sequential) Poisson sample.

replicates

[integer(1) >= 0] A positive integer that gives the number of bootstrap replicates (1,000 by default). Non-integers are truncated towards 0.

tau

[numeric(1) >= 1 | function] A number greater than or equal to 1 that gives the rescale factor for the bootstrap weights. Setting to 1 does not rescale the weights. This can also be a function that takes a vector of bootstrap adjustments and returns a number larger than 1. The default automatically picks the smallest feasible rescale factor (up to a small tolerance).

dist

[function] A function that produces random deviates with mean 0 and standard deviation 1, such as rnorm(). The default uses the pseudo-population method by |beaumont+patak2012|section 4.1; see details.

tol

[0 <= numeric(1) < 1] A non-negative number, strictly less than 1, that gives the tolerance for determining the minimum feasible value of tau.

Details

Replicate weights are constructed using the generalized bootstrap method by beaumont+patak2012. Their method takes a vector of design weights \(w\), finds a vector of adjustments \(a\) for each bootstrap replicate, and calculates the replicate weights as \(a w\).

There are two ways to calculate the adjustments \(a\). The default pseudo-population method randomly rounds \(w\) for each replicate to produce a collection of integer weights \(w'\) that are used to generate a random vector \(b\) from the binomial distribution. The vector of adjustments is then \(a = 1 + b - w' / w\). Specifying a deviates-generating function for dist uses this function to produce a random vector \(d\) that is then used to make an adjustment \(a = 1 + d (1 - 1 / w)^{0.5}\).

The adjustments can be rescaled by a value \(\tau \geq 1\) to prevent negative replicate weights. With this rescaling, the adjustment becomes \((a + \tau - 1) / \tau\). If \(\tau > 1\) then the resulting bootstrap variance estimator should be multiplied by \(\tau^2\).

References

*

See Also

sps() for drawing a sequential Poisson sample.

bootstrapFP() (with method = "wGeneralised") in the bootstrapFP package for calculating the variance of Horvitz-Thompson estimators using the generalized bootstrap and make_gen_boot_factors() in the svrep package.

Examples

# Make a population with units of different size
x <- c(1:10, 100)

# Draw a sequential Poisson sample
(samp <- sps(x, 5))

# Make some bootstrap replicates
dist <- list(
  pseudo_population = NULL,
  standard_normal = rnorm,
  exponential = \(x) rexp(x) - 1,
  uniform = \(x) runif(x, -sqrt(3), sqrt(3))
)

lapply(dist, sps_repweights, w = weights(samp), replicates = 5, tau = 2)