# nsize: Required Sample Size In BSDA: Basic Statistics and Data Analysis

## Description

Function to determine required sample size to be within a given margin of error.

## Usage

 `1` ```nsize(b, sigma = NULL, p = 0.5, conf.level = 0.95, type = "mu") ```

## Arguments

 `b` the desired bound. `sigma` population standard deviation. Not required if using type `"pi"`. `p` estimate for the population proportion of successes. Not required if using type `"mu"`. `conf.level` confidence level for the problem, restricted to lie between zero and one. `type` character string, one of `"mu"` or `"pi"`, or just the initial letter of each, indicating the appropriate parameter. Default value is `"mu"`.

## Details

Answer is based on a normal approximation when using type `"pi"`.

## Value

Returns required sample size.

Alan T. Arnholt

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12``` ```nsize(b=.03, p=708/1200, conf.level=.90, type="pi") # Returns the required sample size (n) to estimate the population # proportion of successes with a 0.9 confidence interval # so that the margin of error is no more than 0.03 when the # estimate of the population propotion of successes is 708/1200. # This is problem 5.38 on page 257 of Kitchen's BSDA. nsize(b=.15, sigma=.31, conf.level=.90, type="mu") # Returns the required sample size (n) to estimate the population # mean with a 0.9 confidence interval so that the margin # of error is no more than 0.15. This is Example 5.17 on page # 261 of Kitchen's BSDA. ```

BSDA documentation built on July 30, 2017, 5:01 p.m.