Expiry

How setting an expiry works for surveys

definitions:

• expire_invitation: time until which somebody has to have accessed the survey
• expire_inactivity: time for how long somebody has to have been inactive before survey expires (after starting)
• grace_period: time after starting by which one has to be finished, relative to expire_invitation

scenarios:

1. invitation should be valid for 7 hours, people should be able to edit for at most 8 hours:
   • expire_invitation: 7*60, grace_period = 30, expire_inactivity = 0
   • can result in people loading a a page at 7:59, submitting a page at 8:01 and having data lost
   • result:
     • for someone who never reacted: 7*60
     • for someone who clicks at 6:50, then is inactive: 7:30
     • for someone who clicks at 6:50, then waits 5minutes, then fills out within 20 minutes: 7:15
     • for someone who clicks at 6:50, then waits 20minutes, then fills out 1 item every 10 min: is interrupted 7:30
2. invitation should be valid for 7 hours. once started, people should not be locked out unless they're inactive for more than 30m
   • expire_invitation = 7*60, grace_period = 0, expire_inactivity = 30
   • can result in people stringing out a session for hours (but unlikely user behaviour)
   • result:
     • for someone who never reacted: 7*60
     • for someone who clicks at 6:50, then is inactive: 7:20
     • for someone who clicks at 6:50, then waits 5minutes, then fills out within 20 minutes: finishes 7:15
     • for someone who clicks at 6:50, then waits 20minutes, then fills out 1 item every 20 min: finishes unpredictably late
3. invitation should be valid for 7 hours, people should be able to edit for at most 10 hours, but only if they stay active
   • expire_invitation = 760, grace_period = 360, expire_inactivity = 30
   • result:
     • for someone who never reacted: 7*60
     • for someone who clicks at 6:50, then is inactive: 7:20
     • for someone who clicks at 6:50, then waits 5minutes, then fills out within 20 minutes: finishes 7:15
     • for someone who clicks at 6:50, then waits 20minutes, then fills out 1 item every 20 min: is interrupted 10:00
4. invitation should be valid for 7 hours, as soon as people react, they have unlimited time to fill out
   • expire_invitation = 7*60, grace_period = 0, expire_inactivity = 0
   • result:
     • for someone who never reacted: 7*60
     • for someone who clicks at 6:50, then is inactive: never
     • for someone who clicks at 6:50, then waits 5minutes, then fills out within 20 minutes: finishes 7:15
     • for someone who clicks at 6:50, then waits 20minutes, then fills out 1 item every 20 min: finishes unpredictably late