Ask three data modelers for their definition of a conceptual data model. You will get three answers that on the surface seem similar. Ask them to dive deeper into their understanding of conceptual modeling. That is where the definitions diverge. Data modelers are pretty much on the same page when it comes to logical and physical modeling. Conceptual modeling is another story.
There is either a passion or lack of passion for conceptual data modeling that is fodder for discussion across the modeling community. Personally, I am a proponent of adopting a conceptual modeling practice that fits your organizational needs and not an intellectual exercise from a textbook that was implemented because the author said you had to do it.
To arrive at that best fit for your organization, It is good practice to walk through the time tested five Ws – who, what, when, where, and why. This formula works as well for making technical decisions as it does for building your household budget. Here are some five Ws to get you thinking about the use of conceptual data models in your organization.
WHO
Who creates the model? Who is involved in the modeling exercise? Who is the target audience? Data modelers are involved in most conceptual modeling efforts. Since the model captures business information requirements, a business systems analyst or business person may be responsible or partially responsible for the artifact. It is important to have the right people engaged in the modeling process. This assures the model tells the business’s information story to the correct audience in a way that is clearly understood.
WHAT
What is the purpose of the model? What is the level of detail? What happens after it is complete? Having a good handle on the value an artifact brings before creating the artifact makes sure it meets the expected results. I have seen conceptual models with a wide variety of detail. Each organization must determine what level of detail is appropriate to their organization. Knowing what happens to the model after completion factors heavily into what is required or not required to add value.
WHEN
When do you create the model? When do you not create the model? When do you consider it complete? Modeling occurs throughout the development lifecycle. For some, the conceptual model is a throw away project artifact. For others it is a living breathing artifact beyond the project’s duration. Modeling is typically linear: conceptual -> logical ->physical. Viewing an enterprise model from a conceptual perspective necessitates a variance from this linear path.
WHERE
Where is the model created? Where will the target audience view it? Knowing the resources and efforts your organization is willing to expend in a conceptual modeling initiative drives where the model resides. For some, the model is on a piece of paper; for others a PowerPoint slide or Visio diagram; and for some in a data modeling tool such as CA ERwin. I favor the data modeling tool route since it gives more usability of the modeled artifacts and connects the business model to the subsequent IT based models
WHY
Why does the business community need a model? Why does IT need the model? As good stewards of the corporate information asset, data modelers need to speak on behalf of the whys. There is good support for business and IT use of conceptual models. There are also exceptions when the model is not needed. The speed of IT today necessitates taking good hard looks at artifacts and their place in our development methods.
WIKIPEDIA SAYS
Sometimes Wikipedia hits a definition head on and other times it leaves the reader even more confused. I entered “conceptual data model” and was redirected to “conceptual schema”. It nicely states what a conceptual data model is. Now you just have to apply some of the five Ws for your organization.
“This is a high-level description of business informational needs. It typically includes only the main concepts and the main relationship among them. Typically this is a first-cut model, with insufficient detail to build an actual database.” – Wikipedia
Tom Bilcze
I am presenting at Enterprise Data World 2014 in Austin , Texas. I hope that you will join me in my session: And Other Duties As Assigned – Embracing New Roles to Grow in Your Enterprise. #EDW14