Greg; On this point, I agree with you on this issue. The relationships reflected in the data dictionaries are a product of the need expressed by the experts at the point of care. These Entity Relationship Diagrams are after-the-fact depictions of such hard won rules which have been honed against the grind stone of reality with lots of adjustment to reflect the fine tuning that the application requires to better serve the needs of the patients. What we have here is a model which adapts to the needed changes quickly.
The information in those ER Diagrams would look a lot different and be much less well adjusted to the needs of the end users if they were developed as requirements in isolation from the point of care. The result would be something less. ----- Original Message ----- From: "Gregory Woodhouse" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Saturday, June 11, 2005 8:27 PM Subject: Re: [Hardhats-members] == VistaWeb Missing Apps == > One further thought. What is complexity? Is it something that can > accurately be measured by the number of nodes in an ER diagram, or is > there more to it than that? > === > Gregory Woodhouse > [EMAIL PROTECTED] > > "It is a capital mistake to theorize before one has data." > --Sir Arthur Conan Doyle > > > > On Jun 11, 2005, at 7:51 PM, Chris Richardson wrote: > > > Want an idea of the complexity of the VistA model? Look up the > > Entity > > Relationship Diagrams. Then show one of the nearly 100 pdf files > > to your > > favorite Relational Database Guru and watch him blanch at the > > numbers of > > data elements and relationships represented there. On CHCS there > > were over > > 22,000 different data elements in the data dictionary. In Northern > > California, nearly 500,000 patient records are stored in less than 120 > > gigabytes of disk space. It would be interesting to see how much > > space the > > same information would take up in the relational model, then pack a > > lunch, > > cause it will take a good long time to traverse that data as a > > relational > > database. > > > > > > ------------------------------------------------------- > This SF.Net email is sponsored by: NEC IT Guy Games. How far can you shotput > a projector? How fast can you ride your desk chair down the office luge track? > If you want to score the big prize, get to know the little guy. > Play to win an NEC 61" plasma display: http://www.necitguy.com/?r=20 > _______________________________________________ > Hardhats-members mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/hardhats-members > > ------------------------------------------------------- This SF.Net email is sponsored by: NEC IT Guy Games. How far can you shotput a projector? How fast can you ride your desk chair down the office luge track? If you want to score the big prize, get to know the little guy. Play to win an NEC 61" plasma display: http://www.necitguy.com/?r=20 _______________________________________________ Hardhats-members mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/hardhats-members
