The abstract, although it comes first logistically, always should be written last. It needs to be written last because it is the essence of your report, drawing information from all of the other sections of the report. It explains why the experiment was performed and what conclusions were drawn from the results obtained. A general guideline for an abstract has five sections or areas of focus: why the experiment was conducted; the problem being addressed; what methods were used to solve the problem; the major results obtained; and the overall conclusions from the experiment as a whole. Do not be misled, however, from this list into thinking that the abstract is a long section. In fact, it should be significantly shorter than all of the others. All of this information should be summarized in a clear but succinct manner if the abstract is going to be successful. An estimated average length for all of this information is only a single paragraph. Although this may seem as though it is a short length to contain all of the required information, it is necessary because it forces you to be accurate and yet compact, two essential qualities.
The best way to attempt to go about writing an abstract is to divide it into the sections mentioned above. The first two sections are very similar and can be grouped together, but do not have to be. If you decide to address them separately, make sure that you do not repeat anything. Often a section can be mentioned in only one sentence. Remember, brevity is the key to a successful abstract. Each section is addressed below to help clarify what needs to be included and what can be omitted.
The most important thing to remember when writing the abstract is to be brief and state only what is pertinent. No extraneous information should be included. A successful abstract is compact, accurate and self-contained. It also must be clear enough so someone who is unfamiliar with your experiment could understand why you did what you did,
Links: Pechenik, Jan A. A short guide to writing about Biology. pp. 54-102, Tufts University: Harper CollinsCollege Publishers. 1993. Viewed on line 9/27/12: http://writing2.richmond.edu/training/project/biology/abslit.html: