Table 1.

Goals, methods, spirit of inquiry, and milestones, by phase, in the ORBIT model

PHASE	CENTRAL GOAL	SPECIFIC GOALS	COMMON METHODS	SPIRIT OF INQUIRY	MILESTONE
Phase Ia: Define	Define basic elements	Develop hypothesized pathway by which behavioral treatment can solve important clinical problem Provide scientific basis for behavioral milestones Provide basic behavioral/social science basis for treatment components and their respective treatment targets Identify appropriate subjects Assess safety, tolerability, acceptability	Review of clinical guidelines, meta-analyses, clinical trials, basic behavioral/social science findings, epidemiologic studies. Experiments Time Series ABA designs N-of-1 trials Ecological observational studies Formative qualitative research: focus groups interviews Evidentiary studies	Creativity Discovery Flexibility Experimentation Hypothesis formulation	Candidate treatment components, methods, and milestones are defined.
Phase Ib: Refine	Refine for strength and efficiency	Identify independent and interactive treatment components Determine needed dose/duration Determine mode of delivery Determine need for tailoring for: special populations treatment response If needed, optimize treatment using basic behavioral/social science findings Assess safety, tolerability, acceptability	Factorial/fractional factorial designs Adaptive designs Experiments Time series Adaptive treatments Formative qualitative research: focus groups interviews Signal detection methods	Efficiency Tailoring Clinical relevance Sensitivity to patient Optimization Flexibility	Satisfaction that the treatment package is complete and the fixed protocol is ready for testing
Phase IIa: Proof-of-Concept	Clinically significant signal	Prepare the Treatment Manual and procedures for fidelity monitoring. Determine whether the treatment can achieve a clinically significant signal on the behavioral risk factor	Quasi-experimental, treatment-only design	Test of a fixed protocol	A clinically significant impact on the behavioral target
Phase IIb: Pilot Testing	Clinically significant signal over noise	Replication of clinically significant signal in treated Clinically significant signal over noise Adequacy of control group: minimal change in behavioral risk factor minimal dropouts and crossovers credible and acceptable	Randomized designs	Randomized test of a fixed protocol Systematic study of control group	Empirical support that: the intervention has a clinically significant signal over the control group the control group is appropriate
Feasibility Pilot	Feasibility of efficacy trial protocol	Prepare the Manual of Operations for trial protocol Determine logistical feasibility of trial protocol for investigators and participants Provide estimates needed for design of efficacy trial: screening to enrollment ratio dropout/crossover rates response rates in treated and control conditions	Qualitative and quantitative studies of feasibility & acceptability	Acceptability to target population Performance across multiple sites Preparation for efficacy trial sample size length of follow-up number of sites	Empirical support that the trial protocol is logistically feasible Empirically derived estimates available for the design of an efficacy trial