
MECE Segmentation - mutually exclusive and collectively exhaustive
MECE is a method of segmenting data into mutually exclusive and collectively exhaustive sub-elements. To put it another way, elements should “exclude” each other, that is, they should be different, and they should “exhaust” the relevant field, that is, they should contain all that belongs to it. When creating an issue tree for your case structure, MECE should be utilised as a method. This will help you prevent dependencies between distinct branches of the tree, allowing you to separate sub-problems properly.
MECE segmentation is an effective way to structure the analysis while solving a case study.
Mutually Exclusive: seeks to simplify things by avoiding overlaps. You must ensure that the possible solutions or groups are not considered twice by mistake
Collectively Exhaustive: ensures a complete collection without leaving any options. All potential options have been studied exhaustively
Let’s learn the difference between MECE and Non-MECE
Let's take the example of the famous game - “Among Us”. We have two types of character/group there – the crewmates and the imposters!
Now imagine there are 4 imposters and 5 crewmates! ( Who do you think will win here?)
Characters in both the groups have their own goals and these goals are not similar, right? And there is no 3rd kind of character

This is an example of mutually exclusive and exhaustive when no person can be in both groups - mutually exclusive - but every person is in either one of them – collectively exhaustive! – MECE! And Peace!
Now imagine, you are playing Among Us with one of your friends on a live call and your friend got the imposter role and you got the crewmate's role. After disclosing the roles to each other, you decided to play dirty to your crewmates ( or to your group) by masking your friend's role as a crewmate (during the vote-kick out session, by the way, have you ever done this kind of act?)
Now to everyone, your friend is a crewmate but in actuality, he/she is an imposter!

This is an example of not exclusive and not exhaustive (for not-exhaustive imagine someone who is facing a huge lag and is not playing at all)
I hope now you are now clear with the concept of MECE.