nsize {BSDA}  R Documentation 
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 = "mu")
b 
the desired bound. 
sigma 
population standard deviation. Not required if using type

p 
estimate for the population proportion of successes. Not required
if using type 
conf.level 
confidence level for the problem, restricted to lie between zero and one. 
type 
character string, one of 
Answer is based on a normal approximation when using type "pi"
.
Returns required sample size.
Alan T. Arnholt
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.