## 5 Analysis of Influencing Factors of Urban Vitality  
### Identification of the Key Influencing Factors of Urban Vitality  
By employing the optimal parameter geographic detector for factor detection, the following results were obtained: Among all factors analyzed, only the correlation between morphological compactness and variations in subdistrict-scale vitality intensity failed to reach statistical significance at the 0.05 level, while all other factors exhibited statistical significance, indicating that a variety of variables influence the spatial distribution of urban vitality in Qingdao. Additionally, as illustrated by the q values (Figure 7), the significance of subdistrict-scale factors consistently exceeds that of block-scale factors. At the subdistrict scale, functional density (X3) exhibits the strongest correlation with the spatial distribution of urban vitality within the built environment. Other factors exerting a relatively large impact on subdistrict vitality, in descending order: commercial facilities accessibility (X12), public facilities accessibility (X13), road network density (X11), cultural and leisure facilities accessibility (X14), bus accessibility (X10) and metro accessibility (X9) comprise more than 50% of the spatial distribution of subdistrict vitality in the central area, thereby serving as the primary determinants of vitality intensity. At the block scale, functional density (X3) remains the factor most closely associated with the spatial distribution of urban vitality within the block environment. Other significant factors affecting block vitality, in order of importance, are public facilities accessibility (X13), commercial facilities accessibility (X12), road network density (X11) and cultural and leisure facilities accessibility (X14). These factors are pivotal in shaping the distribution of block vitality intensity. Morphological compactness (X7) demonstrates the lowest explanatory power at both the subdistrict and block scales.  
Figure 6: LISA map of urban vitality in central Qingdao.  
Figure 7: Factor detection results of urban vitality influencing factors.  
Interaction detection allows for a deeper analysis of how driving factors interact and quantify their combined explanatory power. The q values for these interactions surpass those of individual factors (Figure 8), demonstrating that urban vitality intensity results from the synergistic effects of multiple influences. Upon analyzing factor interactions, two primary outcomes typically emerge: bi-factor enhancement and non-linear enhancement, and significant disparities exist in their interactions. Overall, the collaborative effect of morphological compactness (X7) with commercial facilities accessibility (X12) and functional density (X3) exerts the most pronounced impact on subdistrict-level urban vitality. At the block scale, the interaction between functional density (X3) and cultural and leisure facilities accessibility (X14) demonstrates the greatest influence, resulting in a stronger positive impact on urban vitality. Conversely, the combination of morphological compactness (X7) with resident population density (X1) and greening rate (X6) exhibits the lowest explanatory power at the block scale.