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Stratified Random Sampling

Source: R/strata_rs.R
strata_rs.Rd

strata_rs implements a random sampling procedure in which units that are grouped into strata defined by covariates are sample using complete random sampling within stratum For example, imagine that 50 of 100 men are sampled and 75 of 200 women are sampled.

Usage

strata_rs(
  strata = NULL,
  prob = NULL,
  prob_unit = NULL,
  n = NULL,
  n_unit = NULL,
  strata_n = NULL,
  strata_prob = NULL,
  check_inputs = TRUE
)

Arguments

strata

A vector of length N that indicates which stratum each unit belongs to. Can be a character, factor, or numeric vector. (required)

prob

Use for a design in which either floor(N_stratum*prob) or ceiling(N_stratum*prob) units are sampled within each stratum. The probability of being sampled is exactly prob because with probability 1-prob, floor(N_stratum*prob) units will be sampled and with probability prob, ceiling(N_stratum*prob) units will be sampled. prob must be a real number between 0 and 1 inclusive. (optional)

prob_unit

Must of be of length N. tapply(prob_unit, strata, unique) will be passed to strata_prob.

n

Use for a design in which the scalar n describes the fixed number of units to sample in each stratum. This number does not vary across strata.

n_unit

Must be of length N. tapply(m_unit, strata, unique) will be passed to strata_n.

strata_n

Use for a design in which the numeric vector strata_n describes the number of units to sample within each stratum.

strata_prob

Use for a design in which strata_prob describes the probability of being sampled within each stratum. Differs from prob in that the probability of being sampled can vary across strata.

check_inputs

logical. Defaults to TRUE.

Value

A numeric vector of length N that indicates if a unit is sampled (1) or not (0).

Examples


strata <- rep(c("A", "B","C"), times = c(50, 100, 200))
Z <- strata_rs(strata = strata)
table(strata, Z)
#>       Z
#> strata   0   1
#>      A  25  25
#>      B  50  50
#>      C 100 100

Z <- strata_rs(strata = strata, prob = .3)
table(strata, Z)
#>       Z
#> strata   0   1
#>      A  35  15
#>      B  70  30
#>      C 140  60

Z <- strata_rs(strata = strata, n = 20)
table(strata, Z)
#>       Z
#> strata   0   1
#>      A  30  20
#>      B  80  20
#>      C 180  20

Z <- strata_rs(strata = strata, strata_prob = c(.1, .2, .3))
table(strata, Z)
#>       Z
#> strata   0   1
#>      A  45   5
#>      B  80  20
#>      C 140  60

Z <- strata_rs(strata = strata, 
               prob_unit = rep(c(.1, .2, .3), times = c(50, 100, 200)))
table(strata, Z)
#>       Z
#> strata   0   1
#>      A  45   5
#>      B  80  20
#>      C 140  60

Z <- strata_rs(strata = strata, strata_n = c(20, 30, 40))
table(strata, Z)
#>       Z
#> strata   0   1
#>      A  30  20
#>      B  70  30
#>      C 160  40

Z <- strata_rs(strata = strata, 
               n_unit = rep(c(20, 30, 40), times = c(50, 100, 200)))
table(strata, Z)
#>       Z
#> strata   0   1
#>      A  30  20
#>      B  70  30
#>      C 160  40