Using Plus/Delta for Feedback and Improving Social Processes

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.

Figure 1: Plus/Delta from an introduction to lean construction

Why Plus/Delta
+ is positive
  • what has been good about the process so far?
  • What do we want to keep?
Δ is an incremental change
  • 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.

What happens?

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.

  1. No names – there is no need for names – all opinions are equally valid
  2. Record points without comment or defense – this is information for learning and improvement
  3. Consensus is neither required nor expected — though a suggested improvement may need to be agreed at a future meeting
  4. These are individual opinions — contradictory contributions are welcomed
  5. Be as specific as you can about both:
    1. what went well, what you want to keep — and
    2. what improvements you would like to see
  6. Agree how you are going to act on both plusses and deltas
  7. Use the Plus/Delta from the previous meeting to plan the next one
  8. 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.
At the recent IGLC meeting in Dublin Plus/Delta was recorded on flipcharts at the end of each day and in the business meeting many more points were captured during the annual business meeting on Powerpoint for the benefit of the organisers of the next conference in Cusco, Peru.

Plus/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.

Featured Post


Highlighting 12 Papers from the IGLC 2019 Conference

The International Group For Lean Construction (IGLC) is an international conference started in 1993. The IGLC brings together an international community of researchers and industry practitioners each summer to advance the research and practical applications of Lean Design and Construction. This year’s event in Dublin Ireland had around 300 attendees from 38 different countries who presented 130 papers.

In this blog post, I want to highlight 12 papers from the conference. These papers are intended to give the readers of the Lean Construction Blog a good understanding of the major topics discussed in this year’s IGLC. There are many impactful papers that did not make this list and the interested reader is encouraged to view the full archive of papers on the IGLC website. The 12 papers and their abstracts are included below.

International Group for Lean Construction Read more


Applying Choosing by Advantages Across the Design Process Spectrum

Decision-making in the design process is multi-dimensional, involving various stakeholders with diverse perspectives and interests. This results in the need to undertake multicriteria decision-analysis (MCDA). The process of MCDA fundamentally involves breaking the decision problem into elements, evaluating each element separately, and reintegrating the elements for a holistic perspective.

Choosing by advantages (CBA) is a form of MCDA in which decisions are characteristically based on comparing the advantages of alternatives [1]. CBA, as a lean decision system, creates a participative and transparent environment for collaborative and auditable decision-making. The CBA process involves seven systematic steps (Figure 1).

Choosing By Advantages Read more


Step By Step Guide to Applying Choosing By Advantages

Choosing by Advantages (CBA) is a collaborative and transparent decision making system developed by Jim Suhr, which comprises of multiple methods. CBA includes methods for virtually all types of decisions, from very simple to very complex (Suhr 1999).

Decision-making    Choosing By Advantages Read more


An Introduction to Target Value Delivery

Target Value Delivery (TVD) is “a management practice that drives the design [and construction] to deliver customer values within project constraints” (Ballard, 2009). It is an application of Taiichi Ohno’s practice of self-imposing necessity as a means for continuous improvement (Ballard, 2009). Using TVD, the design and construction is steered towards the target cost. A continuous and pro-active value engineering process is utilized during the design phase to quickly evaluate the cost implications of design options. Cost is a [one of many] constraint rather than an output of the design process.

Target Value Delivery     Read more

Copyright © 2015- Lean Construction Blog