Table 2 Data sources, data analysis and quality control methods used

Semi-structured telephone interviews (N = 647)

Interviewer:

For both sources of data:

• How each core element is being implemented

• Trained to take extensive notes, including key verbatim phrases to record content of each interview

• Investigators regularly reviewed interviewer’s and TA providers’ interview summaries and field notes

• Adaptations made to the core elements

• Cleaned each summary note, making sure team had data on each relevant topic in interview guide

• Bi-weekly meetings addressed TA and field notes

• Rationale for adaptation

• Indicated verbatim phrases

• Discussions focused on barriers and facilitators to effective implementation, as well as how to address them in TA

• Problems encountered in implementation

• Ensured accurate record of interview content and interview conditions (i.e., level of rapport, apparent distractions, general level of flow for each interview)

• Field notes, summaries, and analytical codes applied to relevant sections of each summary note were entered into qualitative database

• Approaches used to overcome challenges

Extensive field notes and commentary

TA providers:

• Barriers and facilitators to implementation fidelity

• Had been coordinators in prior efficacy trials, and were extensively trained and supervised in previous research

• Problems encountered in implementation

• Thus had clear understanding of fidelity to original implementation methods

• Approaches used to overcome challenges

• Jotted extensive notes during all TA sessions (delivered by telephone and/or e-mail)

• Subsequently created detailed commentary about each TA session, operationalized as fieldnotes

• Were trained on the study domains (barriers and facilitators to intervention fidelity) to ensure recording of relevant data when topics of interest arose during TA

• Used template for TA fieldnotes, which contained headings for each relevant study topic where notes were taken