Retrospective Smells - When Action Items dont get acted on

As a retrospective facilitator I realise that if action items don't get completed from retro to retro, they can get really frustrating. I've realised that discussion around previous incomplete items can also be a time-sink especially if there's little ownership. A couple of things I like to do as a retrospective facilitator are:

• Use the SMART acronym to drive out action items (Specific, Measurable, Achievable, Relevant, Time Boxed) - Its useful to remember that you have perhaps just a week between retros, so sign up only for what you can complete during the week.
  
• Dont take the onus of driving the actions yourself. Assign an owner to drive it and decide what observable results the group is looking for.
  
• When reviewing the action item, have the owner give an update and see if the group is satisfied. If not, ensure that it doesnt end up being a blame game against the owner and more an exercise to determine why something didn't happen.
  
• Remind the group that improvement is a collective goal and there's a shared responsibility towards it.

Its also important to explicitly identify the action items that may be difficult to achieve. It ensures that the group is aware of the challenges that it could face and avoids disappointment in future meetings.