There’s consensus among data quality experts that, generally speaking data quality is pretty much bad (here, here, and here). Data quality approaches generally focus on profiling, managing, and correcting data after it is already in the system. This makes sense in a data science or warehousing context, which is often where quality problems surface. To quote William McKnight at the first of those sources:
“Data quality is no longer the domain of just the data warehouse. It is accepted as an enterprise responsibility. If we have the tools, experiences, and best practices, why, then, do we continue to struggle with the problem of data quality?”
So if the data quality problem is Garbage In Garbage Out (GIGO), then I would think that it would be easy to find data quality guidelines for app dev, and that those guidelines would be lightweight and helpful to those projects. Based on my research there are few to none such sources (please add them to the comments if you find otherwise).
So, all that said here’s my cut at app dev data quality guidelines by project activity: Continue reading →
As you’ve read on this site and many others, the database world is well into a transition from a relational focus to a focus on non-relational tools. While the relational approach underpins most organizations’ data management cycles, I’d venture to say that all have a big chunk of big data, NoSQL, unstructured data, and more in their five-year plans, and that chunk is what’s getting most of the executive “mind share”, to use the vernacular.
Some are well along the way in their big data learning adventure, but others haven’t started yet. One thing about this IT revolution is that there’s no shortage of highly accessible training options. But several people have complained to me about the sheer quantity of options, not to mention the sheer number of new words the novice needs to learn in order to figure out what the heck big data is.
So here’s a very short list of training options accessible to the IT professional who is a rank big data beginner, starting with a very brief classification of the tools that I hope provides a some context. Continue reading →
His point is, since big data applications are often off the beaten IT path, big data professionals must solve “problems that companies don’t even know they have – as their insights highlight bottlenecks or inefficiencies in the production, marketing or delivery processes,” often with “data which does not fit comfortably into tables and charts, such as human speech and writing.” Continue reading →
Logical data modeling is one of my tools of choice in business analysis and requirements definition. That’s not particularly unusual – the BABOK (Business Analysis Body of Knowledge) recognizes the Entity-Relationship Diagram (ERD) as a business analysis tool, and for many organizations it’s a non-optional part of requirements document templates.
In practice, however, data models in requirements packages often include many-to-many relationships. I’ve heard experienced data modelers advocate this practice, and it unfortunately seems consistent with the “just enough, just in time” approach associated with agile culture.
In my experience unresolved M:M relationships indicate equally unresolved business questions. The result: schedule delays and budget overruns as missed requirements are built back in to the design, or the familiar “that’s not what we wanted” reaction during User Acceptance Testing (UAT). Continue reading →
At the very first TDWI Conference, Duane Hufford described a phenomenon he called “embedded data”, now more commonly called “overloaded data”, where two or more concepts are stuffed into a single data field (“Metadata Repositories,” TDWI Conference 1995). He described and portrayed in graphics three types of overloaded data. Almost 20 years later, overloaded data remains rampant but Mr Hufford’s ideas, presented below with updated examples, are unfortunately not widely discussed.
Overloaded data breeds in areas not exposed to sound data management techniques for one reason or the other. Big data acquisition typically loads data uncleansed, shifting the burden of unpacking overloaded fields to the receiver (pity the poor data scientist spending 70% of her time acquiring and cleaning data!)
One might refer to non-overloaded data as “atomic”. Beyond making data harder to use, overloaded data requires more code to manage than atomic data (see why in the sections below) so by extension it increases IT costs.
Here’s a field guide to three different types of overloaded data, associated risks, and how to avoid them: Continue reading →
I had pondered writing a post called “Requirements Decay” about how requirements don’t last forever. In my research I found that such a post, complete with “my” words “requirements decay” and “requirements half-life”, had already been done comprehensively here. In a compact argument underpinned by half-life mathematics, the anonymous author proposes that a requirement isn’t likely to stand unchanged forever and explores the implications.
For me, requirements decay is an idea that helps us think realistically about project planning and improves our chances of meeting business needs. Continue reading →
Recently, I posted “Interview with a Data Scientist” at my company’s blog site. In it, my friend and colleague Yan Li answers four questions about being a data scientist and what it takes to become one. In my view Yan’s responses provide a bracing reminder that data science is something truly new, but that it rests on universal principles of application development. Continue reading →
Recently there was a great post at Dzone recounting how one “tech savvy startup” moved away from its NoSQL database management system to a relational one. The writer, Matt Butcher, plays out the reasons under these main points:
Application developers and business people accessing relational databases need data dictionaries in order to properly load or query a database. The data dictionary provides a source of information about the model for those without model access, including entity/table and attribute/column definitions, datatypes, primary keys, relationships among tables, and so on. The data dictionary also provides data modelers with a useful cross reference that improves modeling productivity.
It is particularly useful for the dictionary to be a filterable/sortable Excel document, but out of the box ERwin, one of the leading data modeling tools, includes a notably inflexible reporting capability. Luckily, it is possible to directly query the ERwin “metamodel”. However, I found the ERwin documentation a bit hard to decipher and not quite accurate. Hopefully this post will save modelers some steps in figuring out how to query the metamodel.