# Hot Spot Analysis

Identify statistically significant clusters of high and low values using Getis-Ord Gi* statistics.

## Overview

Hot spot analysis uses the Getis-Ord Gi* statistic to identify statistically significant spatial clusters. Features are classified as:

- **99% Hot Spot**: Very high values, 99% confidence
- **95% Hot Spot**: High values, 95% confidence
- **90% Hot Spot**: High values, 90% confidence
- **Not Significant**: No significant clustering
- **90% Cold Spot**: Low values, 90% confidence
- **95% Cold Spot**: Low values, 95% confidence
- **99% Cold Spot**: Very low values, 99% confidence

## Inputs

- **Dataset**: Point or polygon dataset
- **Value Field**: Numeric field to analyze
- **Neighbor Type**: Distance-based or K-nearest neighbors
- **Distance** (if distance-based): Maximum neighbor distance
- **K Neighbors** (if KNN): Number of nearest neighbors

## Outputs

New dataset containing:

- Original geometry
- **Gi* Z-Score**: Standardized z-score
- **P-Value**: Statistical significance
- **Hot Spot Class**: Categorized class
- Original attributes

## Algorithm

1. Calculate spatial weights matrix based on neighbor configuration
2. Compute Getis-Ord Gi* statistic for each feature
3. Calculate z-scores and p-values
4. Categorize into hot spot classes
5. Store results in output dataset

## Example

```json
{
  "dataset_id": 123,
  "value_field": "population",
  "neighbor_type": "distance",
  "distance": 1000
}
```

## Background Jobs

This analysis runs as a background job. See [Hot Spot Analysis Worker](../workers/hotspot_analysis.md) for details.

## Use Cases

- Crime analysis
- Disease clustering
- Economic activity patterns
- Environmental monitoring
- Social phenomena analysis

## Notes

- Requires numeric field with sufficient variation
- Distance should be appropriate for data scale
- KNN method is generally faster for large datasets
- Results depend on neighbor configuration

## Related Documentation

- [Hot Spot Analysis Worker](../workers/hotspot_analysis.md)
- [Analysis API](../api/analysis.md)
- [Live Hot Spot Analysis](hotspot-live.md)