The non-linear influence of urban historical heritage protection on residents' historical perception: An empirical study based on urban health examination data of Nanjing

The “diagnosis-treatment” model of organic linkage between urban health examination and urban regeneration is an important path to solve the problem of urban diseases such as the loss of urban historical heritages. Residents' historical perception is the subjective reflection of urban historical heritages preservation work, and it is the key data source and cooperation channel for linking urban health examination and urban regeneration work. However, the traditional research using questionnaire data to reflect the subjective perception of residents has the problems of insufficient methodological explanatory power and weak applicability of conclusions. Therefore, based on the 2023 Nanjing urban health examination data, this study utilizes the Extreme Gradient Boosting model based on SHAP interpretation (SHAP-XGBoost) to investigate the nonlinear influence and threshold effect of urban historical heritages protection and individual factors on residents' historical perception in the process of urban health examination and urban regeneration. The results show that: (1) Living condition, the protection degree of historical buildings, the highlighting degree of urban traditional features, health condition and education are the five key factors affecting the level of residents' historical perception. (2) The influence of urban historical heritages protection on residents' historical perception level is non-linear, and there are obvious threshold effects. (3) Residents' individual attributes have a differentiated impact on their historical perception level, and there are both linear and non-linear relationships. This study enriches the empirical research on the relationship between urban historical heritage protection and residents' historical perception, and provides reference for the detailed optimization of urban health examination and renewal.