RSNA 2009: Single Source of Truth?

This is the second installment of my discussion following attendance at the RSNA 2009 trade show event at McCormick Place in downtown Chicago. The first installment discussed the faulty findings of one of the research exhibits, followed by my recommendations on how to properly construct the p-chart, a type of statistical quality control chart, provided as part of the exhibit.

Due to its footprint on the trade show floor, even a casual walk through the commercial exhibits would be sure to catch notice of the space occupied by Cerner Corporation, a global supplier of healthcare solutions. As a consultant enterprise architect, however, what immediately caught my attention was Cerner's slogan – apparently trademarked – which reads "Single Source of Truth".

Single Source of Truth? Trademarked? Wait – isn't this a common expression that has been used for years, especially by data architects? My attendance at RSNA 2009 followed shortly after the first of multiple stints at a healthcare insurance company, and I recall the client CIO describing what he needed as "Single Source of Truth". But in revisiting my discussions, I remember that he instead described his needs as "Single Version of the Truth", and later used this phrase interchangeably with "Single Source of Data".

Single Source of Truth. Single Version of the Truth. Single Source of Data. Do all of these phrases mean the same thing? Same difference, you say, right? Well, no, not exactly. I offer this discussion on these differences here because it is common to hear these terms used interchangeably.

"Single Source of Data" (SSOD) typically indicates that every data element is stored exactly once. In other words, every data element is stored in no more than a single row (record or tuple) of a single database table.

"Single Version of the Truth" (SVOT) typically indicates that multiple versions of the truth can exist within an organization. One of the purposes behind a data warehousing initiative is to resolve these versions of the truth and to provide an "official" version of truth to the organization. One common reason multiple versions of the truth can exist is because such data can reside in organizational silos. Bill Inmon, the "father of data warehousing", has eloquently described this concept in material he has written over the years.

"Single Source of Truth" (SSOT) is essentially synonymous with "Single Source of Data". However, once the term "truth" is referenced, it is usually the case that a data warehouse is involved, because while truth is assumed when a data element can only be found in one place, this assumption does not exist when a data element can be found in multiple places. The distinction that can be made between "Single Source of Truth" and "Single Version of the Truth" is that the former can involve linkages to data elements by reference in other locales. When such data elements are updated, propagation is initiated across the enterprise so that duplicate data elements are always updated, resulting in the same "truth" regardless of which element is subsequently read by processes.

Since Cerner Corporation trademarked "Single Source of Truth", it must be the case that no other company has adopted this slogan to identify its goods and services and distinguish them from competitors. Given the history of SSOD, SVOT, and SSOT, however, I find it odd that this trademark was granted. Regardless of whether you agree with the trademark, make sure you clarify what is meant by any expressions that you use so that opportunities for miscommunication are minimized.