Martner 2019.

Study characteristics
Methods	Design: A nonconcurrent multiple baseline across participants design. Three phases were included: Baseline, EC, and EC + CM. Half the participants received the EC phase following baseline; the other half received EC + CM following baseline Recruitment: Community Setting: Set‐up meetings occurred at the University of Florida Behavioral Health and Technology Research Clinic, USA Study start date/Study end date: Not specified.
Participants	Total N: 12 Inclusion criteria: 18 ‐ 65 years old Smoked ≥ 2 years Smoked ≥ 8 cpd on average Smoked in the past 24 hours Expressed a desire to quit smoking (yes/no) Had reliable access to the internet and a computer or smartphone Breath CO ≥ 10 ppm at set‐up Exclusion criteria: Current or previous medical condition that would pose an increased risk to participation Use of benzodiazepines, cocaine, or opiates in the previous 6 months Smoke marijuana more than twice a month Exposed to elevated CO levels (e.g. spouse smokes in house) Pregnant or expected to become pregnant in the next 6 months 58.3% women; mean age 37.5; mean cpd 16.25; mean FTND 5 Motivated to quit: Expressed a desire to quit smoking. E‐cigarette use at baseline: 3 participants never tried an EC prior to the study; 2 owned an EC but quit using it more than a month prior to the study; remaining 7 had tried an EC more than a year prior to the study but never owned one
Interventions	EC: Refillable All participants provided with smokio electronic cigarettes (second‐generation ECs) and V2 e‐liquid with a concentration of 24 mg/ml (2.4%) of nicotine. Researchers provided participants with a copy of the National Cancer Institute’s brochure Clearing the Air (http://smokefree. gov). Then researchers and participants read through a manual that described the study procedures, and showed participants how to use the software to measure CO and how to use the EC Participants initially received EC without contingency for a period of 14 days following the quit attempt. If participants failed to reduce CO levels during this phase, they received contingency management in addition to EC
Outcomes	4 weeks Adverse events and biomarkers: Adverse events collected in 4‐day smoking behaviour questionnaires; eCO Other outcomes measured: acceptability and use of EC; overall experience of study
Study funding	"The study was supported in part by crowd‐sourced funding enabled by Experiment.com. Preparation of this paper was supported in part by Grant P30DA029926."
Author declarations	"The authors declare no conflicts of interest."
Notes	N of 1 (within‐participants randomized design, not between groups). New for 2020 update.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Not randomized
Allocation concealment (selection bias)	High risk	Not randomized
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No details provided.
Selective reporting (reporting bias)	Unclear risk	AEs measured in behavioural change questionnaire but not reported