In Section 12.1, we introduce capture-recapture sampling and discuss its application of it to estimating population size. We then provide the formula for the variance of the estimate. An example is provided for capture-recapture sampling. This is the direct sampling of capture-recapture where both the capture size and the second capture size are pre-determined.

In Section 12.2, we discuss inverse sampling for capture-recapture where the initial capture size is pre-determined but we sample until a fixed number of tagged items are recaptured. Here, the second capture size is random. An example is provided to compute the estimate as well as its estimated standard deviation.

In Section 12.3, the random response model is introduced to promote more truthful answers to sensitive questions. An example is given to illustrate how to compute the estimate as well as its estimated standard deviation.

Lesson 12: Ch. 18.1 of *Sampling* by Steven Thompson, 3rd edition

## Objectives

- Apply the capture-recapture sampling method to estimate the size of a population,
- Distinguish between the capture-recapture method and the inverse capture-recapture method,
- Apply the inverse capture-recapture sampling method to estimate the size of a population, and
- Apply the random response model to address the issue of sensitive questions in survey research.