Projection Of Population Structure Of Liaoning Province Based On Improved Cohort-component Method

Objective: This study aims to use the cohort-component method to predict the future trend of population development in Liaoning Province under the universal two-child policy.At the same time,in view of the uncertainty of the future population,the prediction model is improved,combined with the Lee-Carter model to predict age-specific Fertility rate,and incorporated into the cohort-component method prediction mechanism,and better predictive analysis the population of Liaoning Province,the development trend of the population structure and the changes in the predicted fertility rate after the implementation of the universal two-child policy in the future.To understand the impact of the implementation of the universal two-child policy on the aging of the population,the dependency ratio,and labor supply in Liaoning Province from the future to 2070,in view of the characteristics of future population structure,provide theoretical basis for relevant government departments to adopt relevant policies according to population development trends.Methods: Based on the population fertility rate of Liaoning Province over the years,the Lee-Carter model was constructed,and the weighted least squares method was used to estimate the parameters.The chaotic time series were used to realize the prediction of time parameters,and then the predicted value of the future fertility rate of Liaoning Province was obtained.The Lee-Carter model was incorporated into the tradition The cohort element method prediction mechanism improves the fertility parameter estimation part of the original model,and builds an improved cohort element method prediction model.The traditional cohort element method model and the improved cohort element method model were used to predict the total population of Liaoning Province from 2011 to 2019,and the absolute error,relative error and average absolute error were used to evaluate the accuracy of the prediction results of the improved model.The improved cohort element model with better accuracy is used to predict the development trend of the total population,the total labor force,the aging degree,the number of women and children of childbearing age,and the social dependency ratio of Liaoning Province under the "comprehensive two-child" policy from the future to 2070.Results: The results of the improved model verification showed that the error showed volatility,the maximum relative error was 0.05%,and the average relative error was0.03%.In the next 50 years,the total population of Liaoning Province will continue to decrease.By 2035,the total population will fall below 40 million from 48.32 million in 2015.After 2050,the decline trend slowed down slightly,and it decreased to 24.48 million in 2070.The working-age population in Liaoning Province is declining year by year,and the working population will be below 30 million after 2025.From 2030 to2055,the size of the working-age population shrinks at a rapid rate,and there will be an inflection point in 2055,and the rate of shrinking will slow down.The change in the proportion of the elderly population in the total population shows an overall trend of first rising and then falling.The period from 2015 to 2035 has the fastest growth rate,which is a period of rapid aging development.The year 2055 is an important turning point for the change of the proportion trend,and then it will decrease year by year to 37.89% in 2070.The proportion of children in the total population has been declining year by year,reaching the bottom between 2040 and 2045,at 8.82%,and has continued to rise steadily thereafter.By 2070,the proportion of children in Liaoning Province will reach 12.26%.The proportion of women of childbearing age in the total female population has been decreasing year by year since 2015,reaching the bottom of 26.61% in 2045,and then rising steadily to 31.19% in 2070.The trend of changes in the total dependency ratio and the old-age dependency ratio are basically synchronized,showing an overall trend of first increasing and then decreasing,and reaching the peak in 2060,and gradually falling to 100.00% by 2070.Conclusion: Compared with the traditional cohort element method model,the improved cohort element method forecast model may better fit the changing trend of the future population structure of Liaoning Province.The total population of Liaoning Province will show a negative growth trend in the future;the population structure is characterized by an increase in the elderly population,a decline in the proportion of the labor force,a decline in the number of women of childbearing age,and a continuous increase in the total dependency ratio.The current universal two-child policy cannot alleviate the population structure problems of Liaoning Province in a timely manner,but from the perspective of long-term effects,there is a certain regulation effect.