Bootstrap replicate means (C backend) — core_bootstrap

B resamples of x, drawn with replacement and each the same length as x, with the mean of every resample returned. The resampling uses the core's own 64-bit Mersenne Twister seeded by seed, NOT R's RNG, so a given seed reproduces the same replicates in every binding of the core and R's own random stream is left untouched.

Usage

core_bootstrap_mean(x, B = 1000L, seed = 42L)

Arguments

x: Numeric vector to resample.
B: Number of bootstrap replicates (default 1000).
seed: Seed for the core's generator (default 42).

Value

A numeric vector of length B: the replicate means.

Examples

set.seed(1)
x <- stats::rnorm(50, mean = 5)

reps <- core_bootstrap_mean(x, B = 500, seed = 7)
length(reps)
#> [1] 500

# The replicates centre on the sample mean, and their spread estimates
# the standard error.
c(sample = mean(x), bootstrap = mean(reps))
#>    sample bootstrap 
#>  5.100448  5.097066 
c(bootstrap_se = stats::sd(reps), formula_se = stats::sd(x) / sqrt(length(x)))
#> bootstrap_se   formula_se 
#>    0.1174288    0.1175769 

# A percentile confidence interval for the mean.
stats::quantile(reps, c(0.025, 0.975))
#>     2.5%    97.5% 
#> 4.864298 5.311439 

# Reproducible: the same seed gives the same replicates, and R's own
# random stream is not consumed.
identical(core_bootstrap_mean(x, 100, seed = 1),
          core_bootstrap_mean(x, 100, seed = 1))
#> [1] TRUE