I am doing a study which examines the effect of having choices. Participants are randomly assigned to either choice condition or control condition. Those in the choice condition have choices over which game to play. Those in the control condition have no choice - they are assigned a game to play.
I want to give participants in the control condition the same games chosen by those in the choice condition. That is to say, after a participant in the choice condition chooses a game, the next person in the control condition is assigned to play the same game.
To achieve this yoked design, I set variables to record the number of each game chosen in the choice condition. So if a person in the choice condition chooses Pac-man, then 1 will be added to PACMAN variable. If a person chooses Tetris, then 1 will be added to TETRIS variable. When the next person comes in and is assigned to the control condition, if TETRIS variable is larger than zero, then assign Tetris game to this person and subtract 1 from TETRIS variable.
My question is how to let these variables be passed from one survey taker to another. As far as I know, variables such as embedded data can be passed to each other within the same survey. But they are reset each time a new survey begins.
Greatly appreciate your help!
UPDATE:
Following T. Gibbon's suggestions,
I end up using quotas to record the counts of each game being chosen in both choice condition and control condition. Through the survey logic and javascript, I compared the counts in choice condition and control condition, if the count of a game in choice condition is larger than that in control condition, then that participant gets into the control condition and assigned to play the game.
Very excited to see the yoked design can be implemented through Qualtrics!
The only data store shared across respondents are quotas. Quota counts only go up (no subtracting), so you'd have to adjust your logic a bit. You could use piped quota counts and compare them to one another in the survey flow, but it seems like that would get complex. If I were doing it, I would pass the quota counts to a web service and return flags telling me if the games were chosen of not.