Online Technical Writing: Abstracts

An abstract is a summary of a body of information. Sometimes, abstracts are in fact called summaries—sometimes, executive summaries or executive abstracts. There are different kinds of abstracts�your technical report uses two types: the descriptive abstract and the informative abstract.

The descriptive abstract provides a description of the report's main topic and purpose as well an overview of its contents. As you can see from the example, it is very short�usually a brief one- or two-sentence paragraph. In this report design, it appears on the title page. You may have noticed something similar to this type of abstract at the beginning of journal articles.

In this type of abstract, you don't summarize any of the facts or conclusions of the report. The descriptive abstract does not say something like this:

Problem:  Based on an exhaustive review of currently available 
          products, this report concludes that none of the 
          available grammar-checking software products provides any 
          useful function to writers.

This is the style of summarizing you find in the informative abstract. Instead, the descriptive abstract says something like this:

Revision: This report provides conclusions and recommendations on 
          the grammar-checking software that is currently 
          available.

The descriptive abstract is little like a program teaser. Or, to use a different analogy, it like major first-level headings of the table of contents have been rewritten in paragraph format.

Descriptive abstract on report title page.

The informative abstract, as its name implies, provides information from the body of the report�specifically, the key facts and conclusions. To put it another way, this type of abstract summarizes the key information from every major section in the body of the report.

It is as if someone had taken a yellow marker and highlighted all the key points in the body of the report then vaccuumed them up into a one- or two-page document. (Of course, then some editing and rewriting would be necessary to make the abstract readable.) Specifically, the requirements for the informative abstract are as follows:

• Summarizes the key facts, conclusions, and other important information in the body of the report.
• Usually about 10 percent of the length of the full report: for example, an informative abstract for a 10-page report would be 1 page. This ratio stops after about 30 pages, however. For 50- or 60-page reports, the abstract should not go over 3 to 4 pages.
• Summarizes the key information from each of the main sections of the report, and proportionately so (a 3-page section of a 10-page report ought to take up about 30 percent of the informative abstract).
• Phrases information in a very dense, compact way. Sentence are longer than normal and are crammed with information. The abstract tries to compact information down to that 10-percent level. It's expected that the writing in an informative abstract will be dense and heavily worded. (However, do not omit normal words such as the, a, and an.
• Omits introductory explanation, unless that is the focus of the main body of the report. Definitions and other background information are omitted if they are not the major focus of the report. The informative abstract is not an introduction to the subject matter of the report�and it is not an introduction!
• Omits citations for source borrowings. If you summarize information that you borrowed from other writers, you do not have to repeat the citation in the informative abstract (in other words, no brackets with source numbers and page numbers).
• Includes key statistical detail. Don't sacrifice key numerical facts to make the informative abstract brief. One expects to see numerical data in an informative abstract.
• Omits descriptive-abstract phrasing. You should not see phrasing like this: "This report presents conclusions and recommendations from a survey done on grammar-checking software." Instead, the informative abstract presents the details of those conclusions and recommendations.

This last point is particularly important. People often confuse the kinds of writing expected in descriptive and informative abstracts. Study the difference between the informative and descriptive phrasing in the following examples:

Informative:  Based on an exhaustive review of currently 
              available products, this report concludes that 
              none of the available grammar-checking software 
              products provides any useful function to writers.

Descriptive:  This report provides conclusions and recommendations
              on the grammar-checking software that is currently 
              available.

                            ABSTRACT


     Computerized speech recognition takes advantage of the most
     natural form of communication, the human voice. During
     speech, sound is generated by the vo cal cords and by air
     rushing from the lungs. If the vocal cords vibrate, a voiced
     sound is produced; otherwise, the sound is unvoiced. The
     main problem in speech recognition is that no two voices
     produce their sounds alike and that an individual voice va-
     ries in different conditions. Because voices do vary and
     because words blend together in a continuous stream in
     natural speech, most recognition systems require that each
     speaker train the machine to his or her voice and that words
     have at least one-tenth of a second pause between them. Such
     a system is called an isolated word recognition system and
     con sists of three major components that process human
     speech: (1) the preprocessor which removes irregula rities
     from the speech signal and then breaks it up into parts; (2)
     the feature extractor which extracts 32 key features from
     the signal; and (3) the classification phase which
     identifies the spoken word and includes the training mode
     and reference pattern memory. Spoken words are identified on
     the basis of a certain decision algorithm, some of which
     involve dynamic programming, zero crossing rate, linear pre-
     dictive coding, and the use of state diagram.
     
     Voice recognition systems offer many applications including
     data entry, freedom for mobility, security uses, telephone
     access, and helpful devices for the handicapped. However,
     these same systems also face problems such as poor
     recognition accuracy, loss of privacy among those who use
     them, and limited vocabulary sizes. The goal of the
     industry is the development of speaker-independent systems
     that can recognize continuous human speech regardless of
     the speaker and that can continually improve their vo-
     cabulary size and recognition accuracy.

Informative abstract. This type summarizes the key facts and conclusions in the body of the report. (By the way, speech recognition has come a long way since this report was written in 1982!)

Coming soon . . .

As you reread and revise your abstracts, watch out for problems such as the following:

• Make sure that the descriptive abstract does not include informative abstract phrasing; make sure that the informative abstract does not include descriptive abstract phrasing.
• Make sure the descriptive overviews all the contents�all the major sections�of the report.
• Make sure that the informative abstract summarizes all the major sections of the report. (And don't forget�the informative abstract is not an introduction!)
• Make sure the informative abstract summarizes all key concepts, conclusions, and facts from the body of the report (including key statistical information).
• Make sure that the informative abstract excludes general, obvious, deadwood information and that the phrasing is compact and concentrated.
• Make sure that the informative abstract is neither too brief (less than 10 percent) nor too long (more than 15 percent).

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