ci.popsize: Confidence interval for an unknown population size

In statpsych: Statistical Methods for Psychologists

Confidence interval for an unknown population size

Description

Computes a Wald confidence interval for an unknown population size using mark-recapture sampling. This method assumes independence of the two samples. This function requires the frequency counts from an incomplete 2 x 2 contingency table for the two samples (f11 is the unknown number of people who were not observed in either sample). This method sets the estimated odds ratio (with .5 added to each cell) to 1 and solves for unobserved cell frequency. An approximate standard error is recovered from the confidence interval.

Usage

ci.popsize(alpha, f00, f01, f10)

Arguments

alpha	alpha level for 1-alpha confidence
f00	number of people observed in both samples
f01	number of people observed in first sample but not second sample
f10	number of people observed in second sample but not first sample

Value

Returns a 1-row matrix. The columns are:

• Estimate - estimate of the unknown population size

• SE - recovered standard error

• LL - lower limit of the confidence interval

• UL - upper limit of the confidence interval

Examples

ci.popsize(.05, 794, 710, 741)

# Should return:
# Estimate       SE   LL   UL
#     2908 49.49071 2818 3012

statpsych documentation built on Sept. 11, 2024, 7:42 p.m.