This book presents the culmination of our collaborative research, going back over 15 years (Rogers & Little, 1994), and for one of us, even longer (Rogers, 1967, 1973). It addresses a dif?cult, yet necessary, area of demographic research: what to do in data situations characterized by irregular, inadequate, or missing data. A common solution within the demographic community has been what is generally referred to as "indirect estimation." In our work the focus has been on the indirect estimation of migration, and our use of the term "indirect" follows the description given in the 1983 United Nations manual, which de?ned it as "techniques suited for analysis of incomplete or defective demographic data" (United Nations, 1983, p. 1). We wrote this book with a goal to make it accessible to a reader familiar with introductory statistical modeling, at the level of regression and categorical data an- ysis using log - linear models. It is primarily intended to serve as a reference work for demographers, sociologists, geographers, economists, and regional planners.

This book presents the culmination of our collaborative research, going back over 15 years (Rogers & Little, 1994), and for one of us, even longer (Rogers, 1967, 1973). It addresses a dif?cult, yet necessary, area of demographic research: what to do in data situations characterized by irregular, inadequate, or missing data. A common solution within the demographic community has been what is generally referred to as "indirect estimation." In our work the focus has been on the indirect estimation of migration, and our use of the term "indirect" follows the description given in the 1983 United Nations manual, which de?ned it as "techniques suited for analysis of incomplete or defective demographic data" (United Nations, 1983, p. 1). We wrote this book with a goal to make it accessible to a reader familiar with introductory statistical modeling, at the level of regression and categorical data an- ysis using log - linear models. It is primarily intended to serve as a reference work for demographers, sociologists, geographers, economists, and regional planners.

Dr. Albert Schmid President of the Federal Office for Migration and Refugees According to the United Nations, about 200 million people of the estimated world population of 6.8 billion are international migrants - that corresponds to about three per cent of the total world population. The proportion of international migrants in the global population has increased only marginally in the last 40 years. But, as a result of global population growth, the absolute number of migrants has increased, and their structure and spatial distribution has changed considerably. A structural shift has taken place primarily in the industrialised countries, where less than 20 per cent of the global workers are now living, but where more than 60 per cent of all migrants worldwide reside. Since 1990, more than 16 million people have moved to Germany, while about 11 million have left the country in the same period. Altogether, 15 million people of international migration origin are living in Germany, comprising almost 19 per cent of Germany's current population of 82 million. At the end of 2006, about 64 million people out of Europe's population of 732 million, or nine per cent, lived in a European country they were not born in. But why does anybody migrate at all? People decide to leave because, in general, they expect to find better conditions and opportunities in other countries or regions.