Confidence interval for a proportion using inverse sampling

Source: R/statpsych3.R

Computes an exact confidence interval for a population proportion when inverse sampling has been used. An approximate standard error is recovered from the confidence interval. With inverse sampling, the number of participants who have the attribute (f) is predetermined and sampling continues until f attains its prespecified value. With inverse sampling, the sample size (n) will not be known in advance.

ci.prop.inv(alpha, f, n)

Arguments

alpha

alpha level for 1-alpha confidence

f

number of participants who have the attribute (fixed)

n

sample size (random)

Value

Returns a 1-row matrix. The columns are:

  • Estimate - estimate of proportion

  • SE - recovered standard error

  • LL - lower limit of confidence interval

  • UL - upper limit of confidence interval

References

Zou GY (2010). “Confidence interval estimation under inverse sampling.” Computational Statistics & Data Analysis, 54(1), 55--64. ISSN 0167-9473, doi:10.1016/j.csda.2005.05.007 .

Examples

ci.prop.inv(.05, 5, 67)
#>    Estimate         SE         LL        UL
#>  0.07462687 0.03145284 0.02467471 0.1479676

# Should return:
#   Estimate         SE         LL        UL
# 0.07462687 0.03145284 0.02467471 0.1479676