Editorial--Recent developments in capture-recapture methods and their applications.

In recent years capture-recapture methods have experienced important theoretical developments. New application areas have been added to their spectrum, in turn supporting new developments on the methodological side. Hence it appears appropriate to take a closer look at some of these developments. This is the objective of this special theme in the current issue of the Biometrical Journal. The contributions to this special theme stem from a recent Conference of Recent Developments in Capture-Recapture Methods and their Applications (held on July 12–13, 2007, School of Biological Sciences, University of Reading, UK). Capture-Recapture has its origin in the Biological/Ecological Sciences with the work of Lincoln and Petersen. More than one hundred years ago Petersen (1896) published his landmark paper suggesting what later became known as the Lincoln–Petersen estimator, since it was also independently developed by Lincoln (1930). This estimator and its stabilized version developed by Chapman (1951) are still in use by numerous practitioners. In a way, this issue could be considered a celebration of the centenary of the Lincoln–Petersen estimator. Capture-Recapture methods can be seen to be applied in three major sciences, all represented in various contributions of this special topic issue: The biological sciences, where the size of animal populations and their diversity are of importance. The social sciences, where we are interested in the amount of illegal activities, such as illegal immigration. The life and medical sciences, where we often want to know the size of the hidden disease burden in a population, such as depression or drug use. In the biological sciences the classical book by Seber (1982) characterizes the various biological application fields. In addition, the recent monograph by Borchers, Buckland and Zucchini (2002) supplements a view with biological applications using modern inference tools. More recently, capturerecapture methods have been applied to other areas. The landmark paper by Sekar and Deming (1949) applied capture-recapture methods to estimate the number of births and deaths in an area near Calcutta. This paper started a development of the capture-recapture methodology in demography and social science in general. This development was further supplemented and supported by the appearance of the book by Bishop, Fienberg, and Holland (1975) on multivariate discrete analysis in which the entire chapter 6 was devoted to capture-recapture methods. Yet a further milestone was the establishment of the methodology in medicine and public health by the landmark papers by Hook and Regal (1995) as well as the two papers by the International Working Group for Disease Monitoring and Forecasting (IWGDMF 1995a, b). In the early phases the method was used to develop a more com-