This data viz depicts the time until recurring smoking episodes for participants who received a standard care intervention (SC; left set of colored tiers) and those who received standard care plus contingency managements (CM; right set of colored tiers).
Survival analysis is used to model the time until an event (or recurring events) of interest, such as a return to smoking after a period of initial or re-initiated abstinence. Data are structured as episodes. An episode starts on the day when a participant establishes 24 hours of abstinence (day 1) and ends on the day when a participant smokes for the first time since initial abstinence (e.g., day 15). In this case, the time unit of measurement is days, and the time to event for that episode is 15. After this initial return to smoking, episode 1 is complete. If the participant re-establishes abstinence for a period of 24 hours, then episode 2 commences (day 1) and ends on the day when a participant returns to smoking (e.g., day 7). If a participant does not return to smoking for the entire study period, they are right censored.
In the data for the visualization above, all participants started in a period of abstinence and therefore a time series for each participant in the sample is depicted as part of one of the two bottom tiers (shown in navy blue) depending on whether they received the SC (left) or CM (right) intervention. The episode tiers for the CM participants is a mirror image. Number of days between initiating abstinence and a return to smoking are depicted on the x-axis. On the y-axis, participants are vertically stacked in the tier based on an ordering scheme from most (bottom) to least (top) number of abstinence days within the initial abstinence episode (navy blue tier). Participants with a coral dot at the end of their time series are right censored, indicating they did not return to smoking (i.e., maintained abstinence) for all days they participated in the study (max=28 days).
The lighter blue tier (2nd from the bottom) depicts participants who re-initiated abstinence after their first return to smoking.
The dark purple tier (3rd from the bottom) depicts participants who re-initiated abstinence after their second return to smoking.
The light purple tier (4th from the bottom) depicts participants who re-initiated abstinence after their third return to smoking.
The dark teal tier (5th from the bottom) depicts participants who re-initiated abstinence after their fourth return to smoking.
The light teal tier (top) depicts participants who re-initiated abstinence after their fifth return to smoking.