Cluster deduplication threshold

@@ -12,7 +12,7 @@ bcsc_class: current-fact
language_protocol: PROSE-TOPIC
last_edited: 2026-07-11
editor: pointsav-engineering
short_description: "The co-location index pipeline deduplicates overlapping clusters that represent the same commercial zone using a 150-metre threshold, retaining the cluster with the higher secondary operator count. A prior 500-metre threshold was found to suppress legitimately distinct commercial nodes in dense suburban corridors."
short_description: "The co-location index pipeline deduplicates overlapping clusters that represent the same commercial zone using a fixed, tightly-set proximity threshold, retaining the cluster with the higher secondary operator count. An earlier, substantially wider threshold was found to suppress legitimately distinct commercial nodes in dense suburban corridors."
paired_with: site-selection/cluster-deduplication-threshold.es.md
cites:
  - ni-51-102
@@ -25,11 +25,11 @@ The [[co-location-methodology|co-location index]] pipeline produces one cluster 

Large commercial zones frequently host two or more anchor-category stores within metres of each other. A Home Depot and a Costco sharing a parking lot in suburban Edmonton, for example, sit roughly 20 metres apart. Without deduplication, both stores produce clusters with nearly identical catchment geometry, co-tenants, and scores. The map displays two concentric rings covering the same zone — neither wrong in isolation, but together misleading about the number of distinct commercial nodes in that corridor.

## Threshold selection: 0.15 km
## Threshold selection

The deduplication step removes any cluster whose anchor store falls within a fixed radius of a higher-ranked cluster anchor already confirmed for retention. The threshold is set at **0.15 km (150 metres)**. At this distance, only stores that genuinely share a single parking lot or immediate building complex are collapsed. Anchors in adjacent strip malls separated by a service road (typically 200–500 metres apart) are treated as distinct nodes and retained.
The deduplication step removes any cluster whose anchor store falls within a fixed, tightly-set radius of a higher-ranked cluster anchor already confirmed for retention. The radius is narrow enough that only stores genuinely sharing a single parking lot or immediate building complex are collapsed. Anchors in adjacent strip malls separated by a service road are treated as distinct nodes and retained.

An earlier implementation used a 0.50 km threshold. Field review of the Edmonton metropolitan area identified cases where legitimate, separately operated commercial zones were being suppressed without notification: a Walmart-anchored node and a Home Depot-anchored node in neighbouring commercial blocks, serving different residential catchments, were treated as duplicates and one was removed. The 0.50 km threshold proved too coarse for dense suburban corridors in Canadian and North American markets.
An earlier implementation used a substantially wider threshold. Field review of the Edmonton metropolitan area identified cases where legitimate, separately operated commercial zones were being suppressed without notification: a Walmart-anchored node and a Home Depot-anchored node in neighbouring commercial blocks, serving different residential catchments, were treated as duplicates and one was removed. That wider threshold proved too coarse for dense suburban corridors in Canadian and North American markets, and it was tightened accordingly.

## Ranking the survivor

@@ -37,7 +37,7 @@ When two anchors fall within the threshold distance, the retained cluster is the

## Pipeline effect

After applying the 0.15 km threshold, a representative pipeline run produced 6,422 retained clusters from 7,594 candidates — 1,172 same-zone duplicates removed. The reduction is concentrated in dense commercial corridors where multiple anchor formats co-locate in close proximity. Tier distribution and national rankings are assigned after deduplication runs, so the published counts reflect deduplicated zones only. (These figures are from a methodology example run; current production counts are in [[about-regional-markets-system|Regional Markets Intelligence System]].)
After applying the tightened threshold, deduplication removes a meaningful share of candidate clusters as same-zone duplicates in a representative pipeline run. The reduction is concentrated in dense commercial corridors where multiple anchor formats co-locate in close proximity. Tier distribution and national rankings are assigned after deduplication runs, so the published counts reflect deduplicated zones only. Current production counts are published in [[about-regional-markets-system|Regional Markets Intelligence System]].

## See also