2. Materials and Methods
Public spaces for PA were identified through the INEGI National Geostatistical Framework [
18] and OpenStreetMap (for 2024). The National Geostatistical Framework is designed to reference statistical information from INEGI censuses and surveys [
19]. In keeping with the Framework, green areas and medians in urban areas with information updated to 2020 were classified as public spaces for PA. Places associated with public space such as courts, stadiums, gardens, parks, sports units, recreational areas, and green areas were also considered. This information was supplemented by information from the OSM, a publicly accessible tool that is continuously updated with contributions from users. We used information collected in April 2024. Due to the different classifications adopted by OSM, places it classified as parks, fields, and meadows, and points of interest designated as parks were considered public spaces for PA. To avoid duplication in the associated data from the National Geostatistical Framework and OSM, the database was filtered to ensure that only single values for physical activity spaces were included.
The study explores urban areas using the AGEB as the unit of analysis because it is the spatial scale that best describes the availability of public spaces for PA in the everyday dynamics of the population. At the same time, only urban AGEBs are studied, because the quality of the information from both the National Geostatistical Framework and the OSM is usually more reliable for these types of settlements than for rural AGEBs. A total of 66,422 urban AGEBs were identified.
To ensure that the analysis was based on AGEBs with a resident population and explored the surroundings in which this population lived, the AGEBs were divided into quintiles according to the number of inhabited dwellings registered in the 2020 INEGI Population and Housing Census [
19]. AGEBs found in the first quintile, in other words, those that had between 0 and 22 inhabited dwellings, were excluded. The final number of urban AGEBs analyzed was 50,372.
Once the public spaces for PA and the main urban AGEBs inhabited by the population had been determined, the density of public spaces for PA in each AGEB was calculated as the quotient of the number of square meters of public spaces for PA divided by the total population residing in that AGEB, multiplied by 100.
The level of marginalization considered is the 2020 Urban Marginalization Index reported by the National Population Council at the AGEB level [
20]. The index was developed from the socioeconomic indicators in the 2020 Population and Housing Census, such as the percentages of the population between the ages of six and 14 who do not attend school, the population aged 15 or older who do not have basic education, the population without state health insurance, and occupants of private homes lacking drainage, toilets, electricity, and piped water, with dirt floors, overcrowding, and no refrigerator, internet, or cell phone [
20]. A higher level on the 2020 marginalization index indicates that the corresponding AGEB has less social marginalization.
Quartiles were created from the marginalization index for each metropolitan area. The means and medians of the density of spaces for PA were obtained according to these marginalization quartiles. These two measures of central tendency were estimated because the space density variable for PA has a right-skewed distribution. The ANOVA test was used to identify differences between the means of the density of areas for PA based on marginalization, while the Kruskal-Wallis test was used for the medians.
The relationship between the density of public spaces for PA and the marginalization index at the AGEB level was analyzed using the bivariate Moran's I methodology and the analysis of Local Indicators of Spatial Association (LISA) [
21], through which maps were constructed [
22]. We began by defining the proximity between geographical units, and subsequently measured whether the value of a quantitative variable in one AGEB had any relationship to the value of another quantitative variable in neighboring AGEBs, weighting by proximity to calculate the global bivariate Moran’s I. A positive overall bivariate Moran's I value indicates that the general pattern is that high values of one variable at one location tend to be associated with high values of the other variable at neighboring locations. Conversely, LISA maps are a local representation of the spatial association generated by Moran’s I. In other words, regardless of whether there is a global association or correlation, it is possible to visualize clusters of spatial units with a common relationship based on neighboring units. A non-significant value indicates that there is insufficient statistical evidence to assume the existence of a correlation between the value of a variable in each spatial unit and the value of another variable in neighboring spatial units [
22]. We produced the LISA maps under the Queen criterion, whereby AGEBs with an adjacent edge or a vertex in common are considered neighbors. The LISA analysis classifies the units of analysis into five main categories: non-significant, high levels of both variables, low levels of both variables, a high level of one variable with a low level of the other variable, and a low level of one variable with a high level of the other variable.
Since there are marked regional contrasts in Mexico [
23], in addition to the analysis of the entire set of urban AGEBs in the country, separate analyses were also conducted for the subsets of AGEBs in the three most populated metropolitan areas in Mexico, Mexico City, Monterrey and Guadalajara, housing 17%, 4.2%, and 4.1% of the total population of Mexico.
The Moran's I calculation and the LISA analysis were performed as sensitivity analyses by replacing the CONAPO marginalization index with the AMAI socioeconomic status index [
24]. The software used to estimate the Moran's I was GeoDa [
21]. The tool used to analyze the spaces for PA of the National Geostatistical Framework and OSM was Qgis, which made it possible to detect duplicates, eliminate observations that did not correspond to spaces for physical activity, and calculate the area represented by each space and the density of spaces for physical activity in each AGEB.