A Proof-of-concept RCT of Version 3.0 of the Smoking Cessation Smartphone App "Smiling Instead of Smoking" (SiS)

Participants responded to the multiple choice question, "What is your current smoking status?" with answer options: "I smoke daily", "I smoke non-daily (and have smoked in the past 7 days)", "I smoke nondaily (but have NOT smoked in the past 7 days)", and "I do not smoke at all"). If participants reported that they did not smoke at all, they were asked: "Have you been abstinent during the past 30 days?" (yes/no). All participants who reported smoking daily or nondaily to the first question, or who reported not smoking at all but had smoking in the past 30 days, or those who left either of those questions unanswered were marked as NOT 30-day point prevalent smoking abstinent (not included in the abstinent count below). People who reported not smoking at all and being smoking-abstinent for the past 30 days were marked as 30-day point prevalent smoking abstinent (include in the abstinent count below).

If participants report having smoked in the past 7 days, they were asked to indicate how many cigarettes they smoked each day ("Last Monday:, Last Sunday:). Changes in cigarette consumption were calculated by subtracting the number of cigarettes smoked in the week leading up to the baseline assessment, as measured in the baseline survey, from the number of cigarettes smoked in the week leading up to the 2, 6, 12, and 24 week post-quit assessments, as assessed in these respective surveys.

As measured using the Client Satisfaction Scale (CSQ-8) (Larsen, 1979), an 8 item multiple choice measure that will be used to assess participants' satisfaction with the smoking cessation support they receive (e.g., "How satisfied are you with the amount of help you received?"). Scores are summed across items and range from 8 to 32, with higher scores indicating greater satisfaction.

Measured using the following single item, "During this past week, how much time did you spend applying or contemplating the content of the SiS app/QG app/"Clearing the Air"?" [in minutes].

Assessed using a study-specific, unpublished 8-item measure in which participants rated the extent to which they agreed or disagreed with statements about the smoking cessation support they received and the things they did while quitting (5-point Likert scale, 1=strongly disagree, 5=strongly agree, e.g., "I used [the assigned treatment] the way I was supposed to (in the days leading up to and following my quit attempt)." and "I avoided situations that would make me want to smoke."). The scores of the 8 items were averaged, so that scores could range from 1 to 5, where higher scores indicate stronger agreement with the use of a larger combination of smoking cessation strategies (i.e., a more positive outcome).

Assessed using a study-specific, unpublished 17-item measure in which participants rated the extent to which they agreed or disagreed with statements about the helpfulness of their assigned app during the quitting process (e.g., "[the app]...gave me confidence that I can quit smoking.", "[the app]... made me feel that I knew the right steps to take to quit.", and "[the app] ...reminded me in crucial moments to stay quit."). Items were rated on 5-point Likert scales ranging from 1="strongly disagree" to 5="strongly agree". The scores of the 17 items were averaged, so that scores could range from 1 to 5, where higher scores indicate stronger agreement with perceived impact of the smoking cessation support their assigned app provided (i.e., a more positive outcome).

As measured using the Appreciation Scale, (Adler \& Fagley, 2005) an 18-item scale assessing the degree to which one is appreciative. Ten of the items assess frequency of action (e.g., "I do things to remind myself to be thankful", using a 7-point Likert scale of: 1 = "More than once a day" to 7 = "Never"). The remaining eight items assess level of agreement with appreciative statements (e.g., "I feel that it is a miracle to be alive", using a 7-point Likert scale of: 1 = "Strongly agree" to 7 = "Strongly disagree"). Item scores were summed to a total score with a possible range from 18 to 126 where higher scores indicate greater appreciation.

Number of days participants used the assigned app during the prescribed period of app use (i.e., 7 weeks for both apps). App usage is passively recorded by the app, which time-stamps every interaction with the app.

This was assessed via self-reported estimates of app use. Participants were asked on how many days they used the app in weeks 4, 5, and 6 post-quit ("On how many days per week did you use the app?"), and for how many minutes per typical day they used the assigned app ("On the days you used the app, how many minutes per day did you interact with the app?"). The days per week were multiplied by the minutes per app-use-day for each week, then averaged across the three weeks.

Measured using the single item, "How much did you like using the smoking cessation app we asked you to use?" Participants respond on a 5-point Likert scale (1 = I strongly disliked using the app, 2 = I somewhat disliked using the app, 3 = I neither liked nor disliked using the app; 4 = I somewhat liked using the app, and 5 = I strongly liked using the app).

Measured using the single item, "How satisfied are you with the smoking cessation support this app provided you with?" Participants respond on a 5-point Likert scale (1 = very unsatisfied, 2 = somewhat dissatisfied, 3 = neither satisfied nor dissatisfied, 4 = somewhat satisfied, 5 = very satisfied).

As assessed via the System Usability Scale (SUS; Brooke, 1996), a ten-item attitude scale giving a global view of subjective assessments of usability, adapted to include language specific to the smoking app (e.g., "I found the smoking app unnecessarily complex" 5-point Likert: 1 = strongly disagree, 5 = strongly agree). Scale scores range from 0 to 100 with greater scores indicating a more favorable perception of usability of the app.