# nCont: Compute a simple random sample size for an estimated mean In PracTools: Tools for Designing and Weighting Survey Samples

 nCont R Documentation

## Compute a simple random sample size for an estimated mean

### Description

Compute a simple random sample size using either a target coefficient of variation, CV_0, or target variance, V_0, for an estimated mean.

### Usage

nCont(CV0=NULL, V0=NULL, S2=NULL, ybarU=NULL, N=Inf, CVpop=NULL)


### Arguments

 CV0 target value of coefficient of variation of \bar{y_s} V0 target value of variance of \bar{y_s} S2 unit (population) variance ybarU population mean of target variable N number of units in finite population CVpop unit (population) coefficient of variation

### Details

If CV_0 is the desired target, then the unit CV, CVpop, or the population mean and variance, ybarU and S2, must also be provided. If V_0 is the constrained value, then S2 must be also be included in the function call.

### Value

numeric sample size

### Author(s)

Richard Valliant, Jill A. Dever, Frauke Kreuter

### References

Valliant, R., Dever, J., Kreuter, F. (2018, chap. 3). Practical Tools for Designing and Weighting Survey Samples, 2nd edition. New York: Springer.

nLogOdds, nProp, nPropMoe, nWilson

### Examples

nCont(CV0=0.05, CVpop=2)
nCont(CV0=0.05, CVpop=2, N=500)
nCont(CV0=0.10/1.645, CVpop=1)

# Compute sample size for a ratio estimator in smho98 population
# Identify large units to select with certainty first
data(smho98)
cert <- smho98[,"BEDS"] > 2000
tmp <- smho98[!cert, ]
tmp <- tmp[tmp[, "BEDS"] > 0, ]

x <- tmp[,"BEDS"]
y <- tmp[, "EXPTOTAL"]
m <- lm(y ~ 0 + x, weights = 1/x)
ybarU <- mean(y)
S2R <- sum(m\$residuals^2/(length(x)-1))
nCont(CV0=0.15, S2=S2R, ybarU=ybarU)


PracTools documentation built on Nov. 9, 2023, 9:06 a.m.