T-formed ERD is a diagram of how you do business activities, for it collects and analyzes the real data, all the available data in business activities.

　The data comes from various sources:
　(1) "Formal" data available from documents, journals, slips and vouchers, and
　　　the computerized data on screens and reports, and in files.
　(2) "Informal" data obtainable from document being widely current around the workplace.

Note: informal data
　The "informal" data is not a rumor on the grapevine, it's being used as an alternative to the "formal" data, e.g.,
　a computer outputs four reports on sales and there are, to my dismay, four quantitatively different figures of sales in the reports, one for each. The end users are completely confused as to which figure is correct, so they screen their work from the harmful effects of contaminated data by storing (in their PCs or on sheets of paper) data which they really use on site, and which deviates from the formal data. That's the way it is, and their data is the REAL data.

　
● Data-analysis

　Once we finish data-clustering (with formal and informal data), we're expected, now, to form a diagrammatic representation on paper of the ERD.

　Events are disposed (vertically) in historical order; resources are placed above and below the events--it makes no sense to put the resources, if any, in alphabetical order.

　Before you get started with the creation of relationships among entities, you should count up the events and resources; you can conduct an early diagnosis of business activities by "palpation" of data.

　□ If the events outnumber the resoruces,
　　your business may not be kept for years without suffering degradation.

　It is admitted that, with many events and with a good flow of events, we can achieve the efficiency of our work, and that greater efficiency can bring higher productivity.　It will be, however, coming to an end sooner or later as it's getting to the maximum level where you stay put in status quo ante and the (flow of) events may be exposed to a danger of obsolescence with the change of the times.

　□ If the resources outnumber the events,
　　your business may be improving with new events.

　An event is a vehicle of resources [ R(a, b) ], and how about doing it the other way around and creating a new event with a new combination of two resources, and you can get a new event or a new business chance with the (existing) resources.
　We may take some examples next time.