# Ecological Fallacy

Ecological fallacy occurs when conclusions about individual-level behavior are derived from group-level data. In a geospatial context, this can happen when analyzing spatial data: what's true for a region or group may not necessarily be true for individuals within that area. "For example, if we can portray on a map that census tracts that have a higher proportion (say 20%) of adults having attained graduate degrees, and we have another map that shows a strong correlation of the same tracts with higher educational attainment also show a higher than average tendency (say, 20%) of residents use bicycles as their primary mode of transportation to work; [we might be tempted to make a remark that our maps show that people with graduate degrees are more likely to ride bicycles to work](https://www.pbcgis.com/normalize/)."

The ecological fallacy, the risk of [drawing incorrect inferences about individuals based on aggregated data](https://mgimond.github.io/Spatial/pitfalls-to-avoid.html#ecological-fallacy), highlights the importance of scale and data quality in mapmaking. Attempting to represent data with greater precision than provided can mislead, highlighting the responsibility of map makers to ensure their maps accurately reflect the data. In 'Spatial Aggregation and the Ecological Fallacy,' the authors write, "Improved ease of analysis also contributes to the widespread use of ecological data. For example, a geographical information system allows the effective storage and combination of data sets from different sources and with differing geographies \[…]" ([Spatial Aggregation and the Ecological Fallacy - PMC](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4209486/)).

### **Why It Matters**

Ecological fallacy can lead to misleading interpretations in environmental justice issues. For instance, policies based on flawed data analysis may fail to address the needs of marginalized communities within seemingly affluent areas. Accurate data interpretation ensures that interventions are properly targeted and effective, preventing the overlooking of vulnerable populations.

### **Guidance**

* Ask yourself if the scale of your data matches the scale of your conclusions.
* Combine quantitative data with qualitative insights from community engagement to understand the local context better.
* Regularly review and question your analysis assumptions, especially when making policy or community recommendations based on spatial data.

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