CONTEMPORARY ISSUES IN MODELLING POPULATION PROCESSES

With improved data on demographic processes, the need for certain types of mathematical models has diminished gradually. Population censuses, improved vital registration systems, new data sources as Sample Registration Scheme in India, demographic health surveys, national surveys such as National Family Health Surveys in India (NFHS), child and reproductive health survey, have provided quite reliable estimates of various demographic measures along with social class and urban-rural differences. Moreover, demographic transition from high to low death and birth rates is occurring in all countries of the world. Now the issues are no more estimation and prediction of demographic rates and ratios. There are other issues: aging and health at the older ages (Crimmins, 2005; Turra, et al., 2005; Lutz and Scherbov, 2005; Bongaarts, 2006; Jansen and Kunst, 2007), timing of the end of world population growth (Lutz et al., 2003, sexuality (Mensch, 2006, Gabrielli, 2007), determinants of neonatal mortality (Vandresse, 2008), and trends in HIV/AIDS (Bongaarts, 2008).

It may be said that models can be used in any field of demographic interest. What one needs to apply modelling is to have:

• Clarity of objectives

• Appropriate measurement of the variables of the system

• Theory that links the various variables – directly or indirectly

• Mathematical equations to describe the above relationships

• Adequate data of high reliability

• Adequate computing facilities

• Instruments to measure the fitness of the model to real world data

As time passed and demographers took interest in new areas, several new domains of modelling have developed in literature. The area of modelling is going to expand further.