Agile Factory

Constraint Manufacturing - APICS discussion

Plus-Minus-Interesting discussion

From: Steve Holt
Sent: August 16, 2004

I'm reminded of a form of brainstorming I've used for many years. I'd give credit to its source, but I can't remember where I got it!

It's called Plus-Minus-Interesting (PMI). The idea is that there are 3 phases to the brainstorming session. In each phase the typical brainstorming rules apply (one idea per person, complete sentences, etc.) but each phase has its own focus.

During Plus, only positive comments on the topic are allowed. This has the effect of temporarily stopping both naysayers and devil's advocates so that their views are not allowed to stifle the creative comments of the rest of the participants.

During the Minus phase everyone points out problems with the topic. Note that in the Plus phase even people who dislike the idea must come up with things that are good about it and during the Minus phase even those who like the idea must come up with problems with it. This has the effect of not allowing people to argue only in favor of their position.

However, the real value is in the third phase, Interesting.
Here the idea is to essentially finish the sentence, "If we did this, it'd be interesting to see if..." Note that the topics that come up here are ones that are not inherently negative or positive. They often end up being unproven assumptions and/or indications of how others will react. In many of the cases where I've used this method the Plus and Minus phases, the ones traditionally thought to be the value of brainstorming, are really just set ups for the Interesting phase, which actually produces the most valuable comments.

In the naysayer/devil's advocate discussion, I'd expect most naysayer comments to come out during Minus phase along with other negative comments and the devil's advocate comments to come out during the Interesting phase with other challenging but unproven comments and assumptions.

Steve Holt

From: Jim Bowles
Sent: August 16, 2004

PMI is one of Edward DeBonos methods.

He argues that when we think of negative aspects of our lives it effects the "chemical" processes in our heads and makes it difficult for us to then think positively.

So he recommends thinking of the positives first and then the negatives.

I have used and seen this process used effectively in "unblocking" a group when considering taking on new ideas or work practices.

We use the same sequence of PMI with the NBR (from the MSW - TP skill development) process (NBR is Negative Branch Reservation coming from Thinking Process of TOC) when considering the negative side effects of an INJECTION.

Considering the positive reasons of having the INJECTION before considering the negative ones.

Jim Bowles