More than two thirds of the consolidated clusters detected by methods A ∩ B were concentrated in municipalities of 500 to 10,000 inhabitants (55% of the towns) and barely 2% involve towns larger than 50,000 inhabitants (0.3% of all towns) (Table 2). The frequency of detection of consolidated clusters by methods A ∩ B is zero for towns with fewer than 100 inhabitants, and increases with town population up to 50,000 inhabitants. For towns with fewer than 100 inhabitants, only method A detected any clusters. For each method, the distribution of the number of consolidated clusters detected differed by town population-size groups; this difference was substantial for the group of towns with 10,000–50,000 inhabitants, for which method A detected more clusters.

Table 2

Distribution of consolidated clusters detected, according to the population of the affected town (Puy-de-Dôme, Isère and Gironde; 2009–2012)

List A
List B
List A ∩ B
Number of towns
Town size (inhabitants)Number of DCC(%)Number of DCC(%)Number of DCC(%)TotalConcerned by ≥ 1 DCC(%)
(0, 100) (0) (0) (0) 66 (0.0)
(100, 500) 81 (12) 47 (9) 30 (15) 590 27 (4.6)
(500, 2,000) 192 (30) 238 (46) 70 (36) 599 58 (9.7)
(2,000, 10,000) 171 (27) 182 (36) 67 (35) 242 60 (24.8)
(10,000, 50,000) 192 (30) 41 (8) 23 (12) 41 16 (39.0)
(50,000 et + (1) (1) (2) (20.0)
Total 641 (100) 513 (100) 193 (100) 1,543 162 (10.5)
List A
List B
List A ∩ B
Number of towns
Town size (inhabitants)Number of DCC(%)Number of DCC(%)Number of DCC(%)TotalConcerned by ≥ 1 DCC(%)
(0, 100) (0) (0) (0) 66 (0.0)
(100, 500) 81 (12) 47 (9) 30 (15) 590 27 (4.6)
(500, 2,000) 192 (30) 238 (46) 70 (36) 599 58 (9.7)
(2,000, 10,000) 171 (27) 182 (36) 67 (35) 242 60 (24.8)
(10,000, 50,000) 192 (30) 41 (8) 23 (12) 41 16 (39.0)
(50,000 et + (1) (1) (2) (20.0)
Total 641 (100) 513 (100) 193 (100) 1,543 162 (10.5)

DCC = detected consolidated cluster.

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