Table 3.

Hierarchical regression analysis assessing the influence of subject, tooth and site characteristics in the variability of clinical attachment level (CAL) gain

Intercept	ΔCAL Baseline-6months
	Empty model β±SE	Multivariate model β±SE
	2.974±0.095	3.743±0.225
Patient (Level 3)	0.317±0.081 (16) ‡	0.237±0.059 (-25%)•
Tooth (Level 2)	1.183±0.054 (60) ‡	0.732±0.034 (-38%)•
Site (Level 1)	0.461±0.009 (24) ‡	0.308±0.006 (-33%)•
Total variance	1.961	1.277
-2 LL	17083.055	12305.077*

^‡Proportion of variability in ΔCAL provided by the multilevel analysis at the subject, tooth, and site levels.

^•Change in the proportion of variability in ΔCAL at the subject, tooth, and site levels when explicatory factors were incorporated in the analysis.

^*Variation in -2 LL was significant (P<0.001).