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Inclusion probabilities: Simple Random Sampling

Source: R/simple_rs.R
simple_rs_probabilities.Rd

Returns each unit's probability of being sampled under simple random sampling. Every unit is sampled independently, so the probabilities do not depend on which other units were drawn.

Usage

simple_rs_probabilities(
  N,
  prob = NULL,
  prob_unit = NULL,
  check_inputs = TRUE,
  simple = TRUE
)

Arguments

N

The number of units in the sampling frame. Must be a positive integer. (required)

prob

The probability of being sampled; must be a real number between 0 and 1 inclusive and of length 1. (optional)

prob_unit

The probability of being sampled for each unit; must be a real number between 0 and 1 inclusive and of length N. Because units are drawn independently, this probability may differ from unit to unit. (optional)

check_inputs

Logical. Whether to verify before sampling that the arguments are internally consistent: that probabilities lie between 0 and 1, that vectors are of length N, and that only one of prob and prob_unit is supplied. Defaults to TRUE. Set to FALSE to skip the checks when drawing many samples from arguments that have already been verified; declaring the design once with declare_rs() and drawing from it with draw_rs() does this for you. (optional)

simple

Logical. Internal use only; leave at its default. simple_rs always draws units independently, and this argument exists so that the argument checker knows as much. (optional)

Value

A numeric vector of length N giving each unit's probability of being included in the sample.

Details

These are the quantities inverse-probability weights are built from: weight each sampled unit by the reciprocal of its inclusion probability, which obtain_inclusion_probabilities() extracts for you.

See also

simple_rs()

Examples

probs <- simple_rs_probabilities(N = 100)
table(probs)
#> probs
#> 0.5 
#> 100 

probs <- simple_rs_probabilities(N = 100, prob = 0.3)
table(probs)
#> probs
#> 0.3 
#> 100