NASA TM-105419

Chapter 5—Results and Discussion

The presentation and discussion of the results is the heart of the technical report. Many readers, of course, are interested only in obtaining the quick review of the work afforded by the Summary and the concluding section. But readers who have reason to study the entire text of a report will normally spend most of their time on the Results and Discussion section.

The first purpose of this section is a well-organized and objective presentation of the results. Tables and figures that show the results should have sufficient supporting description to permit the reader to interpret them quickly and accurately. But do not repeat in words what is already apparent from examination of the tables and figures. The second purpose of this section is a discussion of the results, together with their analysis, to show that the conclusions are warranted. Each major conclusion should be clearly explained and compared with the results of similar work by other investigators.

This chapter describes the mechanics for achieving these purposes. The organization, the methods of presentation, and the discussion of results are described. Several examples illustrate the principles involved.

Organization of Section

The Results and Discussion section should present the data as concisely and clearly as possible. To achieve this goal, prepare a good outline of this section before starting to write.

Conventionally, an introductory statement is used to remind readers of the type of tests conducted and the scope of the investigation. Any other statements necessary for correctly interpreting the results should be made in this introductory paragraph.

An important decision is whether to present this material as a single section or as two separate sections, one entitled "Results" and the other "Discussion." Regardless of the length of the report, a single section combining the results and their discussion is usually preferable because this scheme is clearer and less repetitious.

Separate sections may sometimes be desirable:

  1. When heterogeneous data must be considered in making a point in the discussion

For example, the use of separate sections may be better when reporting test data on several materials to determine which is best for a particular application. In this case the test results for each material would be presented in the Results section. The Discussion section would then be used to compare the properties of the various materials, to review their advantages and disadvantages for the application being considered, and finally to select the best material.

  1. When a large number of similar curves must be compared on a single figure

If your data fall too close together to be presented on a single plot, you can present the original data in separate figures and later combine only the faired curves (using different types of lines) from these figures on a single figure for comparison and discussion. The report may well be written with these two sections separated. A lengthy presentation of results about which there is little or no discussion is best made in an appendix. Then only the comparison figure need be shown in the Results and Discussion section, with reference made to the appendix.

If this section is longer than approximately one page, use the pertinent subheadings determined during your preliminary outlining. Perhaps the most frequently used type of outline groups similar data. Another type of outline groups the data obtained with each of several systems being compared.

Avoid promises of NASA research to be published and references to work in progress. Such suggestions in no way enhance the value of the report and might stimulate inquiries that could prove embarrassing if redirection of a worker's activities leaves such promises unfulfilled. If results indicate the need for further research, a simple statement to this effect should suffice.

Presentation of Results

Data should be presented as clearly and simply as possible. Although you are familiar with the work, others are not. Avoid taking too much for granted; avoid complicated correlations; avoid making the presentation too long and too involved with insignificant details. First present the data in a simple, readily understood form. Then if necessary, give complicated comparison figures or correlation curves that make sense only to those fully familiar with the field. In preparing the figures and tables take care to put them in acceptable form.

Including a summary data table is sometimes desirable. The table should include the data necessary for your readers to evaluate the accuracy of your plots and correlations. Additional data may be included to enable them to devise additional plots and correlations. For the sake of brevity present only the most important data in the summary table. But if calculated data are very important and are widely used in the report, include them in the summary data table even though the reader could obtain these values by independent calculations.

Discussion of Results

The discussion of the results is one of the most important parts of a technical report. To discuss the results adequately, you must clearly understand their significance. This requires that you have mastery of the theory pertaining to your field and broad knowledge of the information already available from work in this and allied fields. The discussion must clearly point out the exact contribution made to the existing fund of knowledge by the new data. If the results have an immediate application, point this out. If possible, give an example to illustrate the method of application. Clearly state any significant conclusions and either prove or properly qualify them. But discuss the results; do not merely recapitulate them. The major results and the conclusions, normally stated in both the Summary and the concluding section, must be clearly established here.

Any new or unusual result should be explained. If you do not understand the phenomenon or if the data are too limited to permit rigorous analysis, it is sometimes worthwhile to present a speculative discussion outlining several possible causes. Alert your readers that such a discussion is speculative.

The discussion of the results sometimes includes the method of computation or derivation, normally presented in the Analysis or Procedure sections. Such situations may arise when one figure is derived from preceding figures. If the method is involved, include a complete example as an appendix and indicate only the main steps here.

Again, judgment must be exercised to achieve the desired result. Essential information must not be kept from the reader. But trivial details must be subordinated by placing them in an appendix to avoid diluting the text and obscuring the important facts. End the discussion with a short summary explaining the significance of your work. "When you describe the meaning of your little bit of truth, do it simply. I believe that the simplest statements evoke the most wisdom; verbose language and fancy technical words are used to convey shallow thought" (ref. 2).

Questions on policies and procedures should be directed to Natalie Henrich, (216) 433-5301.

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