Rule of 7-15

I have been writing a short book over the last few months, so I haven’t had time to post an article. But I worked up an idea for the book that I thought I would share on my blog. I call it the Rule of 7-15.

The Rule of 7-15 is an easy way to figure out where a proposed project would fall on the Stacey Matrix just by doing a little easy addition in your head. If you are unfamiliar with the Stacey Matrix, I suggest you read my article: Scrum vs. Waterfall—Just Pick One.

As I mentioned in the Scrum vs. Waterfall article, Waterfall is perfect for simple projects, while complicated, political, and complex project would tend to do better under Scrum. Think of the Stacey matrix as a 10 by 10 grid, with 5 along the bottom axis landing right at the bottom of the “simple” arc and 5 on the left axis landing to the left of the “simple” arc.

The first step is to talk to the stakeholders, product owner, team members, etc. and get consensus on how much agreement and how much certainty there is in the project. Agreement is how much the various stakeholders agree on what to build, consider how much agreement there is on such things as the problem statement, requirements, features, etc. Certainty is a measurement of risk. How certain are you that the solution will actually solve the problem and that the project team can build the solution?

Once you have numbers that represents agreement and certainty, simply add those numbers together. If the combined value is less than 7, then the project is probably a simple project and could probably be done with a waterfall project task list. If the number is greater than 15, there is probably way too much disagreement and uncertainty to proceed with the project. However, a smaller project that reduces the disagreement and/or the complexity might be able to be carved out of it.

If it is exactly 7 or 15, then the project is right on the edge. A small project with a score of 7 would pose little risk and could probably be done as Waterfall. A large project with a 7 could go either way, Waterfall or Scrum, but I would lean toward Scrum. For a project with a combined score of 15, A Scrum project may work, but a reduction of the disagreement or uncertainty would be very beneficial, if this is possible. A value of 8 to 14 is almost certainly a candidate for Agile.

Here are the rules in a nutshell:

  • 2 to 6 » Use Waterfall.
  • 7 » Probably Scrum, but use Waterfall if the team is too small for Scrum.
  • 8 to 14 » Use Scrum.
  • 15 » Tread lightly, but use Scrum if the decision to proceed is made.
  • 16 to 20 » Reduce the complexity or disagreement before starting.

Of course the Stacey Matrix is just a guideline, so the team will have to use their own judgment, but the matrix is a tool that can help guide the team to a sound decision.

See you next time…