20.109(S07):Guidelines for writing a lab report

A formal lab report is the principle way scientific data are conveyed to the rest of the scientific community and preserved for future examination. Each scientific journal has its own idiosyncrasies regarding particulars of the format, but the most common elements of a scientific report, in order of presentation, are:


 * Title
 * List of Authors
 * Abstract
 * Introduction
 * Materials and Methods
 * Results, including figures and tables
 * Discussion
 * References

The requirements for each section are outlined below. This information is given in the order that you might actually write your report rather than the order in which the parts are presented in the final report. If you want more information, you can find parts of this text in an on-line collection of instructional materials used in the Purdue University Writing Lab (http://owl.english.purdue.edu). Other parts are inspired by Robert A. Day’s book, “How to Write and Publish a Scientific Paper” from Oryx Press, a copy of which is available in the teaching lab.

Authors
This is often the subject of many heated discussions and hurt feelings when only one report can be submitted to describe many people’s work. Since each of you will submit your own report, questions about who the authors will be, in what order, and what responsibilities each will have are moot. However you should list the name of your partner on your report since she contributed to the work.

Figures and tables
Some readers begin by scanning the figures first. The figures, with the legends, should provide a self-explanatory overview of your data. Decide what the data show, then create figures which highlight the most important points of your paper.

Tables are used to present repetitive data that is numerical. Graphs or illustrations, collectively called figures, are used to present numerical trends, raw data (like a picture of a gel), or a model that explains your work.

When you prepare your figures and tables, keep in mind that it is significantly more expensive for journals to publish figures and tables than text, so try to present the data in a way that is worthy of such added expense. The table below is an example of an ineffective table.

Temperature		Repeats		Cortical Cells		Ion Flow 24°C		       5		+             		+ 24°C		       5		-             		-

The information in Table 1 could be presented in one sentence, such as: “In ten experiments carried out at 24°C, ion flow was detected only in the presence of cortical cells.” This is a clearer and more concise way to present the information. In addition, all tables and figures must have numbers, titles and legends.

Figure and table legends
Legends to the figures and tables explain the elements that appear in the illustration. Conclusions about the data are NOT included in the legends. As you write your first draft, state in a short simple sentence, what the point of the figure or table is. In later drafts, make sure each element of the figure or table is explained. Your figure legends should be written in the present tense since you are explaining elements that still exist at the time that you are writing the paper.

Results
To write the results section, use the figures and tables as a guide. Start by outlining, in point form, what you found, going slowly through each part of the figures. Then take the points and group them into paragraphs, and finally order the points within each paragraph. Present the data as fully as possible, including stuff that at the moment does not quite make sense.

Verbs in the results section are usually in the past tense. Only established scientific knowledge is written about in the present tense, “the world is round,” for example. You cannot presume that your own data are part of the body of established scientific knowledge, and so when you describe your own results, use the past tense, “a band of 1.3 kb was seen,” for example. There are, however, exceptions to this general rule. It is acceptable to say, “Table 3 shows the sizes of the DNA fragments in our preparation.” It is also acceptable to say, “In a 1991 paper, Ebright and coworkers used PCR to mutagenize DNA.”

Materials and methods
This is like a cooking recipe. Include enough detail so that someone can repeat the experiment. It is important that the reader be able to interpret the results knowing the context in which they were obtained.

The Materials and Methods section should be written in the past tense, since your experiments are completed at the time you are writing your paper.

Discussion
This is the section of the paper for you to show off your understanding of the data. You should summarize what you found. Explain how this relates to what others have found. Explain the implications.

Introduction
Introduce what your question is. Explain why someone should find this interesting. Summarize what is currently known about the question. Introduce a little of what you found and how you found it. You should explain any ideas or techniques that are necessary for someone to understand your results section.

Abstract
The abstract is a very short summary (usually around 150-250 words) of what the question is, what you found, and why it may be important.

The importance of abstracts is increasing as more scientists are using computers to keep up with the literature. Since computers can only search for words in a paper’s title and abstract, these may be the only parts that many people read. The abstract may also be the way a journal’s editor decides whether to send your paper out for peer review or reject it as uninteresting and not generally relevant. Consequently, a well written abstract is extraordinarily important.

Title
The title should be short (about 10 words), interesting, and it should describe what you found.