How to design a Source to Target Matrix

After working a Source to Target Matrix (STTM) for weeks I came to a rather disappointing conclusion ... we laid out the matrix by sources and a developer can't pick that up and start developing. To say the least I was upset at myself and frustrated that we needed to reorganize this document again.  So I decided to pass on this piece of advice to you so you don't have to go through this like did.

Organize your STTM by targets and not sources

The target is what the developer is using as a starting point.  As a result, the developer needs to have his work, the mappings, organized by targets.  I'm not suggesting deviating from the left to right convention of source to target, but rather building a STTM for each target.  In many cases this means having a Excel tab for each target.

Sounds simple enough, right?  In reality it is simple but the complexity comes in how the information is gathered or relayed from clients.  If you start conversations with the client in the context of a target the approach is straight forward.  But that's not reality.  Clients start by talking about sources because that is what they know.  At the end of that session you end up with one source and multiple targets and a document you need to reorganize.

Have migration conversations with clients in the context of the target and save everyone the time of reorganizing and confirming the requirements

This approach is rooted in the principle of beginning with the end in mind.  In my experience, when everyone understands the goal in detail it is much easier, efficient and accurate to hit the target (no pun intended! Well maybe a little).