Plus/Delta is a great way to improve almost any social process. Also known as Do again / Do better and Plus / Change, it is a very simple formative feedback process that only requires 5-10 minutes, a flip chart and pens.
Many meetings that we attend are part of a series, like the weekly commitment planning meeting in Last Planner®, a weekly design review meeting, a quarterly phase planning meeting or an annual conference. These are social processes and, like everything else we do, can be improved.
Plus/Delta takes 3-8 minutes at the end of a meeting, and 1-2 minutes at the beginning of the next. Like all great lean processes, it helps people learn and improve the meeting or other social process they are involved in.
Why Plus/Delta+ is positive
- what has been good about the process so far?
- What do we want to keep?
- how specifically might we improve this process in the future?
Not everyone calls the process Plus/Delta. Rebecca Snelling of JE Dunn Construction prefers Do again/Do better as this is more descriptive of what the process focuses on. Others call it Plus/Change.
At the end of a regular event (or part way through longer events like workshops) spend 5 to 10 minutes collecting feedback about what was good about the meeting that you’d like to do again next time and what you would like to improve and specifically how you would like it to be improved at the next meeting.
things that went well
things to improve next time
|Process is clearer now||Not everyone is here|
|Shorter meetings in future||Prepare Make Ready form before meeting|
|Prepare WWP form before meeting|
|Switch mobile phones off or to silent|
Figure 2: An example from a Last Planner meeting – alternating colours helps participants distinguish points.
- No names – there is no need for names – all opinions are equally valid
- Record points without comment or defense – this is information for learning and improvement
- Consensus is neither required nor expected — though a suggested improvement may need to be agreed at a future meeting
- These are individual opinions — contradictory contributions are welcomed
- Be as specific as you can about both:
- what went well, what you want to keep — and
- what improvements you would like to see
- Agree how you are going to act on both plusses and deltas
- Use the Plus/Delta from the previous meeting to plan the next one
- Bring the record to the next meeting to remind everyone
Why use it?
Summative evaluation at the end of a process does nothing to improve the process in use. As a formative evaluation, Plus/Delta enables a process to be continually improved. The pluses prevent the baby being thrown out with the bathwater while the focus on specific ideas for improvement keeps everyone positive while letting everyone see what can be improved.
If you are ever tempted to try to use an evaluation like this …
1. How satisfied were you with XXX?
2. What did you like most about XXX?
3. What did you like least about XXX?
4. How likely are you to attend one of our XXX in the future?
5. How likely are you to recommend our XXX to a friend?
… try Plus/Delta — you will get far more information that you can act on. Plus/Delta is designed to support learning & improvement while giving all participants in the event or experience an equal voice so that in a few short minutes it addresses the two pillars of lean, Continual improvement and Respect for people.
What’s the history?
Originally developed by the Boeing company in the early 1980s, someone introduced it to Neenan, a construction company in Colorado, in the mid to late 1990s. That’s where Hal Macomber learnt it. Hal says he taught it to Greg Howell and Glenn Ballard in about 1998 and it was very quickly incorporated into the Last Planner® System and into LCI and IGLC meeting processes. Since then it has been used regularly in the Lean Construction community. It is also used in schools and universities to help students improve the conditions for their own learning (see below).
Plus / Deltas can be applied to any activity, idea, experience, work product or action. By focusing on change (rather than what was wrong or didn’t go well), participants are more likely to implicitly share their true assessments while generating improvement ideas.Use it to improve:
- a multi-day workshop or conference: use plus/delta at the end of each day or half-day to improve the rest of the workshop/conference; use overall plus/delta at the end to help improve the next one. For a large conference have one flipchart each for plus and delta and two scribes – or use a “powerpoint” form
- a regular meeting or class: review at the end of each and use the feedback to improve the next one.
- a webinar series: review at the end and record the feedback in a two column “powerpoint” form
- a series of publications: review each publication with plus/delta as it comes out and use the resulting output to improve the next document.
SummaryPlus/Delta is a quick, simple, low-tech way to generate formative and non-threatening feedback to help improve social processes.
This blog uses ideas from: Helminski, L. & Koberna, S. (1995). Total quality in instruction: A systems approach. In H. V. Roberts (ed.), Academic initiatives in total quality for higher education pp.309-362. Milwaukee, WI: ASQC Quality Press.