Methodological Diversity and Statistical Approaches in Urban Vegetation Inequality Research: A Systematic Review (2004–2023)

Urban vegetation indices are important tools for investigating the uneven distribution of green spaces and their links to social, health, and environmental inequities. Despite its increasing use, methodological diversity frequently produces confused or contradictory outcomes. This scoping analysis combines 66 peer-reviewed studies published between 2004 and 2023 to identify the leading approaches, statistical instruments, and indicators used to assess urban vegetation inequality. The analysis shows a prevalence of the Normalized Difference Vegetation Index (NDVI), with Landsat satellites serving as the primary data source. Census block groups have been the preferred spatial unit for studying urban inequities. The choice of satellites, vegetation indices, spatial scales, and statistical studies varies significantly, with spatial autocorrelation, Pearson's, and Spearman's correlation coefficients being the most widely used. ArcGIS is the most used GIS platform; however, R-Studio and SPSS are often used for statistical analysis. The findings emphasize the critical need for methodological standardization to promote comparability and reliability in urban vegetation inequality research.