A researcher explored the complex and varying factors linked to changes in population based on city size. The findings show that, in medium-sized cities, population shifts relate to the financial strength index as an economic factor.
Globally, aging populations and declining numbers are increasing, but the situation in Japan is particularly severe. Currently, 36.21 million people, or 28.9% of the country’s population, are aged 65 and older. Additionally, 74.6% of the 1,747 cities in Japan are identified as experiencing a population decline, with urban policies struggling to address this issue. However, what specifically influences population changes in cities of different sizes remains unclear.
Dr. Haruka Kato, a junior associate professor at Osaka Metropolitan University, investigated these various factors using the Economic, Social, and Educational (ESE) dataset, which includes 270 indicators for each city in Japan. For the analysis, she employed the machine-learning algorithm XGBoost to examine the nonlinear connections between changes in population from 2005 to 2010 and the other 269 indicators.
The research found that most cities experiencing population decline in Japan are either medium-sized or small. The study revealed that the rate of population change is closely linked to social indicators, such as the number of people aged 0-14 in small cities, natural population changes in medium-sized cities, and migration rates in larger cities. Moreover, in medium-sized cities, population changes are associated with the financial strength index as an economic factor, and in small cities, there’s a connection with the recognition of underpopulated areas in urban planning.
“These findings suggest that urban policies should be tailored to the specific size of each city,” Dr. Kato noted. “Medium-sized cities should develop policies beyond just urban planning, such as childcare programs that aim to enhance natural population growth and improve the financial strength index. On the other hand, small cities should consider the designation of underpopulated areas.”
