Before rushing to solve a problem, every problem solving method recommends to spend meaningful time to analyse, understand and plan the action.
The “is / is not” analysis is a very simple yet powerful tool to help clearing what is in the scope and what is to be left aside.
The principle of “is / is not” analysis is to split a paper board (or any support) in two columns, one for “is” and the other for the “is not”. Consider all data and facts and try to understand what is influencing to the problem and what not.
For instance if the problem is frequent deliveries of non-complying lots to quality standards, following questions may help to sort what is and what is not:
Do we have similar problems with different suppliers?
If not, this supplier may be “in” and will be added in the “is” column. If similar problems happened with different suppliers, the variable “supplier” is to be left out, it “is not” a cause of our problem.
In the same way, the investigation goes on:
- Does it happen with different materials?
- Does it happen a specific day/month/moment?
- Does it happen with different quality control operators?
To go on with questions, do not hesitate to use the 5W2Hs
To me “is / is not” analysis looks like playing mastermind, the game you’ll have to guess a hidden combination by trial-and-error, eliminating step by step what is not relevant/influencing.
Alas, as so often (over)simplistic tools are disregarded despite their power. This kind of analysis is not very often used.