Characteristics of the European Simulation
PAGE 1
THE LOGIC OF THE SIMULATION: 1.
A MODEL OF VOLUNTARY MIGRATION The simulation model of the experience of European migration is summarized below in two graphical forms. Both figures show simplified versions of the demographic logic of domestic and overseas migration. Figure A1 treats whole populations at once; Figure A2 gives attention to the age and sex composition of populations.
In Figure C1, each circle represents a distinct population. At the beginning of each period, we assume the existence of discrete groups known as Rural and Urban populations (in blue). Some people depart from the Rural population each year. In addition, we assume there are groups who departed earlier: the Urban Settlers (in the home country) and the Abroad Settlers (overseas) - these are in yellow. The people taken from the Rural population each year are known as Voyagers (in green). The term "voyagers" refers to persons in the high-mortality period of the first year following their departure, after which they become "settlers." Voyagers undergo an initial mortality, and are then divided into those remaining in their home country as Urban Settlers, and those who voyaged abroad. The latter group undergoes an additional mortality (corresponding to the voyage abroad). (The deaths from these two experiences are shown in red.) In the meantime, all of these populations experience normal births and deaths. At the end of each cycle of enslavement, the surviving voyagers are added into the Urban Settler and Abroad Settler populations, and the next cycle of migration begins.
In Figure C2 much of the same information is presented, but with additional details on age and sex in each population. As before, we assume the existence of discrete groups known as Rural and Urban populations (in blue). In addition, we assume that there are groups who were enslaved earlier: the Urban Settlers (in the home country) and the Abroad Settlers (in the Americas) - these are in yellow. Note that the Urban Settlers are primarily female while the Abroad Settlers are primarily male. The people departing from the Rural population each year are known as Voyagers (in green) - they are mostly young adults, both male and female. Figure A2 does not show their mortality in transit, but it does show the difference between those who will become Urban Settlers (mostly young adult females) and those who will become Abroad Settlers (mostly young adult males).
2.
THE SIMULATION The simulation consists of a computerized implementation of the qualitative model summarized above. This simulation of the demography of European migration enables the user to project the effects of various conditions on the size and composition of the populations involved. The procedure relies on standard demographic techniques: it approximates a continuous analysis of population change by dividing the populations into five-year age groups and assuming that all events take place at the midpoint of five-year periods.
As initial conditions, the simulation assume the discrete groups known as Rural and Urban populations. Members of the Voyager population are enslaved: a given percentage of each age and sex group becomes captive each year. Voyagers undergo an initial mortality, and are then divided into those who settle in urban areas of the home country, and those intended who voyage abroad, who then experience an additional mortality as they travel overseas. For each of these steps, the simulation accounts for the age and sex distribution of events. The simulation keeps track of Rural and Urban populations, Urban and Abroad Settler slave populations, the number of Voyagers each year, and the number of births and deaths for each group. The user may select varying input data files and one run parameter, as follows:
You may run the simulation with the default data files. These data have been selected to estimate the average overall pattern on European migration in the mid-nineteenth century. The user may select alternative input data in one of two ways. New users are encouraged to select data by packaged sets of data files, each of which is labelled by its main difference from the default or average data. More experienced users may with to select data by individual data files, enabling you to select precisely the input data you wish. In addition, it is possible for you to create your own data files and use them in the simulation. |
