R Graphical Manual

Browse All

Last data update: 2014.03.03

R: Required Sample Size

nsize

R Documentation

Required Sample Size

Description

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

Usage

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.

Author(s)

Alan T. Arnholt

Examples

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.

Results


R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> library(BSDA)
Loading required package: e1071
Loading required package: lattice

Attaching package: 'BSDA'

The following object is masked from 'package:datasets':

    Orange

> png(filename="/home/ddbj/snapshot/RGM3/R_CC/result/BSDA/nsize.Rd_%03d_medium.png", width=480, height=480)
> ### Name: nsize
> ### Title: Required Sample Size
> ### Aliases: nsize
> ### Keywords: univar
> 
> ### ** Examples
> 
> nsize(b=.03, p=708/1200, conf.level=.90, type="pi")

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 is 728 . 


>     # 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")

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 is 12 . 


>     # 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.
> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>