Function to determine required sample size to be within a given margin of error
nsize(b, sigma = NULL, p = 0.5, conf.level = 0.95, type = c("mu", "pi"))
the desired bound
population standard deviation; not required if using type "pi"
estimate for the population proportion of successes; not required if using type "mu"
confidence level for the problem, restricted to lie between zero and one
character string, one of "mu"
or "pi"
, or just the initial letter of each, indicating the appropriate parameter; default value is "mu"
Answer is based on a normal approximation when using type "pi"
.
nsize(b = 0.015, p = 0.5, conf.level = 0.95, type = "pi")
#>
#> The required sample size (n) to estimate the population
#> proportion of successes with a 0.95 confidence interval
#> so that the margin of error is no more than 0.015 is 4269.
#>
# Returns the required sample size (n) to estimate the population
# proportion of successes with a 0.95 confidence interval
# so that the margin of error is no more than 0.015 when the
# estimate of the population propotion of successes is 0.5.
nsize(b = 0.02, sigma = 0.1, conf.level = 0.95, type = "mu")
#>
#> The required sample size (n) to estimate the population
#> mean with a 0.95 confidence interval so that the margin
#> of error is no more than 0.02 is 97.
#>
# Returns the required sample size (n) to estimate the population
# mean with a 0.95 confidence interval so that the margin
# of error is no more than 0.02.