Table 3.

Mixed-effects Poisson regression to demonstrate effect of neighbourhood characteristics on variance of the random effect, incidence of hospitalized bacteraemic pneumococcal disease in metropolitan Philadelphia, 2005–2008

Model	Fixed effects in the model	Variance of random effect	P value for testing if variance >0
1	Base model	0·1325	<0·0001
2	Neighbourhood density	0·0849	<0·0001
3	% population black	0·0429	<0·0001
4	% population aged <5 years	0·0985	<0·0001
5	% population aged ⩾65 years	0·1304	<0·0001
6	% <5 years, % ⩾ 65 years	0·0955	<0·0001
7	% black, % ⩾65 years	0·0421	0·0011
8	% black, % <5 years	0·0223	0·0347
9	% black, % <5 years, % ⩾65 years	0·0193	0·0585
10	Density, % black, % <5 years, % ⩾65 years	0·0167	0·0819