# Stratified Random Sampling

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.

strata_rs(strata = NULL, prob = NULL, n = 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) |
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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) |

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. |

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 100Z <- strata_rs(strata = strata, prob = .3) table(strata, Z)#> Z #> strata 0 1 #> A 35 15 #> B 70 30 #> C 140 60Z <- strata_rs(strata = strata, n = 20) table(strata, Z)#> Z #> strata 0 1 #> A 30 20 #> B 80 20 #> C 180 20Z <- 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 60Z <- 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