Continuous quality improvement (CQI) in addiction treatment settings: design and intervention protocol of a group randomized pilot study

Table 1 Percentage point difference detectable assuming control group base rate and intra-cluster correlations

Outcomes	(1) Intra-cluster correlation	(2) Base rate (for control arm)	(3) Percentage point difference detectable
Length of stay > 90 days	0.008	50.0%	10.7
Satisfaction:% rating treatment experience as ‘Very Good’	0.110	52.0%	24.0
% giving counselor a 'Very good’ rating	0.038	78.0%	11.4
Positive compliance	0.002	60.0%	6.6
% weekly or more frequent substance use*	0.048	10.9%	8.3
Employed or in school*	0.150	64.4%	26.0
Positive employment activities*	0.010	16.0%	7.2
Emergency medical care*	0.009	8.2%	4.2
Attended self-help groups*	0.008	75.4%	6.9

* Measured at baseline and follow-up. The power calculations reflect the assumption that the correlation between baseline and follow-up observations of the same measure is 0.7 and that the baseline measure is a covariate in the analytic model.

ISSN: 1940-0640