Multiphasic Response Theory (MR Theory)
An important theoretical perspective in our CHES research is to leverage and advance the theory of the multiphasic response (David 1963). This theory hypothesizes that in the early stages of the demographic transition, households had lower child mortality while fertility was still high, leading to increasing population pressures. Therefore these households had to respond in various ways, including deferring marriage, reducing marital fertility, or out-migration. Taking one response would decrease the chances of taking other alternative responses. This was the situation of Japan and Europe in the 19th century. This theory was later expanded to include economic responses, such as expanding the land area, intensifying agricultural production, or finding off-farm work (Bilsborrow 1987). Therefore facing population pressures, people in developing countries will not only respond through demographic transition, but also through economic responses and technological adaptations.
In one of our CHES projects, we are innovatively testing the theory. At the micro-level (e.g., households), more than two multiphasic responses°™e.g., out-migration, off-farm work, and intensification of agriculture°™are being placed in multilevel simultaneous equations models. Our findings will shed light into what demographic, economic, and/or technological responses will be implemented under what conditions.
Bilsborrow, R. 1987. Population pressures and agricultural development in developing countries: A conceptual framework and recent evidence. World Development 15(2): 183-203.
Davis, K. 1963. The theory of change and response in modern demographic history. Population Index 29(4): 345-366.