Schedule the Unknown Unknowns

Catherine Powell posted a very good and clear article about dealing with possible problems from systems in the test schedule: Problem Types.

She classifies them into:
- Fully understood problems;
- Partially understood problems that can be worked in parallel;
- Partially understood problems that are linear.

What I missed here is considering the risk of problems which we are not yet aware of: the so called unknown unkowns.

Donald Rumsfeld said: "There are known knowns. There are things we know that we know. There are known unknowns. That is to say, there are things that we now know we don’t know. But there are also unknown unknowns. There are things we do not know we don’t know."

I think Catherine covered with her classification almost the whole saying of D. Rumpsfeld:
* Fully understood problems -> things we know that we know
* Partially understood problems -> the known unknowns and the now unknowns

As she mentioned that this can be used to refine the time schedule, the known knowns are already in place, and the fully and partially understood problems have to be considered to estimate some additional time for it.

The unknown unknowns I still miss in the classification. If I understood her correctly she gives the advice to keep investigating and then add them to one of the classifications.

I can imagine that in the time schedule you already reserve time for this. For time reservation you need some solid ground. As we are talking about the unknown unknowns this is certainly missing. Perhaps you can justify that solid ground by investigating how complex the system is and how many questions you still might ask to the system. Based on this you can visualize the field of uncertainty.

Explicitly reserving time for this can help project management to identify the risk that the schedule will exceed. The big challenge is not only to move the unknown unkowns towards the unknown knows section; it will also be a challenge to make this activity accepted by project management.