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Many users approach databases as black boxes, and search them as if blindfolded. This is particularly true for CD-ROM databases that most typically are searched by end-users. This will be true also for the increasingly-popular locally-tape-loaded databases. Commercial online databases are still searched predominantly by trained intermediaries who feel much more at ease in sizing up a database before plunging in.
Sizing up a database is essential for efficient searching, and for putting search results in perspective. Sizing up a database is to know its real dimensions. Though many database publishers advise you about some parameters of a database, these data are often not sufficient or may be easily misinterpreted by the user. Simple and innocent sounding claims about the dimensions of a database might need scrutiny. Publishers could provide more unambiguous information, or one might dig up such information through some test searches. In this article I present some examples to illustrate the hidden dimensions of databases.
THE SIZE OF A DATABASE
When one publisher claims that "our database coverage goes back to 1984. Over 100,000 records are added to the database yearly," one is likely to presume that there are over a million records in the database by the end of 1993. In reality, there are less than 600,000 records in the database because for the first four years of the database coverage, the yearly volume was between 10-18,000 records, and the 100,000 figure is true only since 1990.
Publishers quite often volunteer the size information in absolute numbers, making it easy to see if a database is small, medium, large or extra large, relative to competing databases. Figure 1 shows graphically, the total number of records, i.e., the absolute sizes of ABI/INFORM (730,000), Wilson Business Abstracts (780,000), Management Contents (MC) (305,000), and Economic Literature Index (274,000) as of August 1993. (Figure 1 omitted) (Though MC is available only online, the same pictograph is used as for the others available in both CD-ROM and online, for the sake of simplicity.)
THE WIDTH AND HEIGHT OF A DATABASE
Saying that someone weighs 200 pounds is not informative enough to determine the build of that person. Similarly, you might need to know more of the dimensions of a database of 200,000 records. The width and...