Qualitative GIS and informal settlements: Tailoring a mixed-methods approach in evaluating crucial elements of informal settlements

Informal settlements in Southern Europe present complex socio-spatial challenges distinct from those in the Global South, often suffering from territorial stigmatization and governance vacuums. Traditional Geographic Information Systems (GIS) struggle to integrate subjective, lived experiences into spatial analysis without introducing data inflation, known as verbosity bias. This study evaluated the crucial elements of informal settlements and developed a targeted taxonomy of urban informality for Southern Europe. Focusing on the CEP neighborhood in Palermo, Italy, the research employed an interdisciplinary mixed-methods Qualitative GIS approach. Data collection involved document analysis, field observations, and 27 semi-structured interviews, achieving theoretical saturation. To integrate these narratives with spatial metrics, a novel "Text-to-Space" framework was engineered. Qualitative transcripts coded via Grounded Theory were aggregated within a uniform hexagonal grid. A 'Count Distinct' statistical logic was applied to calculate a composite Semantic Density metric (SDcomp), effectively neutralizing verbosity bias. This standardized data then informed an Optimized Hot Spot Analysis (Getis-Ord Gi*). The spatial visualization revealed coherent and interpretively consistent concentrations of informality narratives, organized by relative confidence tiers that reflect the density of resident testimony rather than frequentist inferential significance. Results demonstrated that housing informality and crime were not endemic to the entire neighborhood. Instead, the data mapped a bi-nodal concentration of opportunistic housing occupations and a multi-nodal "infrastructural belt of decay," both of which strictly align with abandoned architectural structures. These findings refute widespread territorial stigmatization by proving that informal practices function as spatial traps resulting from localized state retreat rather than uniform cultural degradation. The study concludes that the "Text-to-Space" framework successfully translates qualitative human experiences into robust geostatistical metrics. By bridging the qualitative-quantitative divide, this research offers an original, replicable diagnostic protocol that enables urban planners to implement precise, corridor-based upgrading strategies across comparable Mediterranean welfare regimes.