Table 1 Potthoff–Whittinghill test for the existence of a spatial heterogeneity in the incidence of childhood acute leukaemia in France 1990–2000. (a) Spatial heterogeneity over the whole territory (36 343 communes) and (b) Spatial heterogeneity in isolated communes in relation to population density

		Whole period 1990–2000		1990–1994		1995–2000
	Age (years)	No. cases	β̂^a (P -value^b)	No. cases	β̂ (P -value)	No. cases	β̂ (P -value)
(a) Spatial heterogeneity over the whole territory (36 343 communes)
All AL	0–14	4897	0.5% (0.23)	2236	1.2% (0.06)	2261	0.2% (0.38)
	0–4	2471	0.1% (0.40)	1141	0% (0.40)	1330	−0.25% (0.60)
	5–9	1435	−0.5% (0.75)	666	−0.25% (0.62)	769	−0.2% (0.49)
	10–14	991	−0.4% (0.69)	429	−0.2% (0.45)	562	−0.2% (0.56)
ALL	0–14	3993	0.35% (0.32)	1831	1.2% (0.07)	2162	−0.1% (0.52)
	0–4	2045	0.05% (0.40)	851	0.3% (0.28)	1094	−0.2% (0.54)
	5–9	1208	−0.5% (0.73)	559	−0.4% (0.77)	649	0.03% (0.34)
	10–14	740	−0.4% (0.67)	321	−0.6% (0.95)	419	−0.3% (0.62)
AML	0–14	837	−0.5% (0.74)	374	0.3% (0.18)	463	−0.4% (0.70)
	0–4	395	0.01% (0.32)	179	0.6% (0.07)	216	−0.2% (0.48)
	5–9	205	−0.3% (0.63)	94	−0.1% (0.47)	111	−0.2% (0.74)
	10–14	237	−0.2% (0.47)	101	0.1% (0.13)	136	−0.15% (0.45)

		1990–2000		1990–1994		1995–2000
		No. cases	β̂^a (P -value^b)	No. cases	β̂ (P -value)	No. cases	β̂ (P -value)
(b) Spatial heterogeneity in isolated communes in relation to population density
	0–14
	Isolated communes	1469	0.1% (0.29)	700	1.6% (0.04)	769	−0.2% (0.41)
	⩽50 inhab/km²	554	0.0% (0.28)	239	0.1% (0.27)	315	0.5% (0.14)
	>50 inhab/km²	915	0.5% (0.39)	461	5.5% (0.01)	454	−2.3% (0.92)
	0–4
	Isolated communes	733	0.2 (0.34)	355	0.3% (0.29)	378	−0.3% (0.53)
	⩽50 inhab/km²	292	0.1% (0.34)	125	−0.5% (0.50)	167	−0.1% (0.34)
	>50 inhab/km²	441	0.5% (0.35)	230	2.5% (0.10)	211	−0.9% (0.64)
	5–9
	Isolated communes	423	−0.8% (0.86)	196	−4.3% (0.66)	227	−0.5% (0.63)
	⩽50 inhab/km²	151	−0.7% (0.64)	64	−0.3% (0.17)	87	−0.4% (0.28)
	>50 inhab/km²	272	−1.3% (0.77)	132	−0.8% (0.64)	140	−0.6% (0.57)
	10–4
	Isolated communes	313	−0.2% (0.55)	149	0.0% (0.34)	164	−0.3% (0.48)
	⩽50 inhab/km²	111	−0.3% (0.43)	50	−0.2% (0.11)	61	−0.3% (0.15)
	>50 inhab/km²	202	−0.1% (0.49)	99	0.5% (0.32)	103	−0.2% (0.40)

Isolated communes: non attractive communes, in terms of employment, that are included in a unit with less than 5000 inhabitants (Rudant et al, 2005).
^aFollowing (Alexander and Boyle, 1996), the ratio of the variance to the mean of the number of cases in any area was equal to 1+β.
^bThe Statistical significance level was based on the one-sided tail probability of the null distribution (1000 Monte Carlo simulations).
The Statistical significance level was based on the one-sided tail probability of the null distribution (999 Monte Carlo simulations).

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