Abstract
Occupancy is a widely used variable to describe spatial distributions of organisms. Although the statistic is easier to collect than other population indices, such as abundance, it often suffers from the problem of false absence arising when the detection rate of the target organisms is below 1. Imperfect detectability can cause serious bias in the estimation of relationships between occupancy and environmental factors and, thus, should be considered explicitly in the statistical model. In this paper, I present an introduction to a statistical model for species occupancy data with imperfect detectability using simple examples. Additionally, I explain appropriate survey strategies when imperfect detectability is inevitable.
