Table 3.

T-tests between and within 38 Boston neighborhoods; Testing change in collective efficacy for families 2006 to 2010

3a. Between Neighborhoods Paired t-test; N=38
Mean (SD)
2006	2010	t	p-value	p
−.13(.42)	−.02(.37)	−2.15	0.04	*

3b. Within Neighborhoods t-test; N=5125, stratified by neighborhood
Without Bonferroni			With Bonferroni†
#	%	p-value	#	%	p-value
significant tests (of 38)	significant tests		significant tests (of 38)	significant tests
3	8%	0.05	0.00	0%	0.001

^#p<.10

^*p<.05

^**p<.01

^***p<.001

^†Bonferroni correction is .05 divided by the number of tests; for each neighborhood cluster (n=38) we are testing one outcome for 38 neighborhoods, so .05 is divided by 38.

NOTES: The sample size for section 3a is 38, because the t-tests are done using neighborhood level data; the sample size for section 3b is 5125, because the t-tests are done at the individual level, but stratified by neighborhood -- the neighborhood specific sample sizes range from 4 to 203 cases.