Guidelines for Writing a Lab Report

Guidelines for Writing a Lab Report

Preparatory comments The format of scientific writing is more restricted than a short story or novel. Scientists, when reporting their research results to a journal, are not given wide latitude with respect to style, but must follow carefully scripted conventions. Each portion of a lab report (lab summary), has a particular limited purpose. All of the parts integrate into a meaningful whole, which precisely reports the results and importance of that research study. A note before you begin. Certain practices are appropriate for a college-level assignment and certain practices are not appropriate. For example, it is expected that all written work will be typed (word processed). Also, the use of lined notebook paper is not appropriate for a laboratory report, because it indicates work in progress and not the finished product. Completed work should be stapled. Additionally, poor syntax, incorrect spelling, etc., are also non-acceptable practices for any college-level writing assignment. Researchers in biology communicate the results and significance of their work by publishing articles in professional journals, where they will be seen and read by other investigators. Laboratory reports are written in the same general format as journal articles to communicate research in an effective and scientific manner. A laboratory report provides a formal record of an experiment. The discussion of objectives, procedures, and results should be specific enough that interested readers could replicate the experiment. Format Although most laboratory reports will include the following sections, some experiments will require a different format. You will work on one section of a lab report each week, until Lab 7, when you put all the components together. Abstract: a brief informational synopsis of your experiment, typically under 200 words. Strive to use informational or declarative rather than descriptive prose. Introduction: identifies the experiment to be undertaken. Explains its objectives and significance, and provides the background necessary to understand it. When appropriate, the background should indicate theoretical predictions. Materials and methods: details how you tested your hypothesis, including experimental procedures, the materials and equipment (you may identify these as they are discussed, rather than listing them separately); the location of the study; and any statistical techniques used. The reader should be able to reproduce your experiment after reading this section. Results: conveys results relevant to the goals of the experiment. Highlights the important findings of the experiment. Considers presenting information visually with graphs and tables. Discussion: this section places specific results into the context of the experiment as a whole. Analyzes and describes the implications/ evaluates the results in light of the objectives stated in the introduction. A Guide to Writing Laboratory Reports 2

Bibliography (or Literature Cited): lists all the outside sources used to support the introduction of the questions and the conclusions, as they relate to previously conducted studies. General comments Scientific research demands precision. Scientific writing should reflect this precision in the form of clarity. Unfortunately, a glance at almost any scientific journal will reveal that the above-stated ideal is often not attained in the real world of scholarly publication. Indeed, many of the accusations by non-scientists of "obscurity" and "elitism" within the scientific community probably originate in the fact that many scientists are not capable of expressing their hypotheses and conclusions clearly and simply. In practical terms, the first of those two suggestions implies that as much effort and consideration should be given to the organization of the paper as was given to the execution of the study, and the second implies that the writer should employ crisp sentences not cluttered with excess verbiage. The purpose of this handout is to help you achieve your goals. Do not consider the following guidelines presented in this guide as unbreakable rules. In other words, there is often more than one "correct" way of doing something, depending on your intentions. However, the practices adopted here are straightforward and intuitively simple. You are advised to become familiar with details of organization, section headings, methods of data presentation, and ways of citing and listing references by examining recent papers in any well-established scientific journal. Guidelines for Writing The scientific paper has the following elements: title, abstract, introduction, methods, results, discussion, and literature cited. The actual words "introduction," "results," etc., are used to head the sections of your paper. Tables and figures are commonly placed at the end of the text. Title: The title should contain three elements: 1. The name of the organism studied; 2. The particular aspect or system studied; 3. The variable(s) manipulated. Do not be afraid to be grammatically creative. Here are some variations on a theme, all suitable as titles: a) The effect of temperature on germination of corn b) Does temperature affect germination of corn? c) Temperature and corn germination: Implications for agriculture Sometimes it is possible to include the principal result or conclusion in the title: High temperatures reduce germination of corn A Guide to Writing Laboratory Reports 3

Abstract: The abstract is a one or two paragraph condensation (150-200 words) of the entire work described completely in the article. The abstract should be a self-contained unit capable of being understood without the benefit of the text. It should contain these four elements: 1. The purpose of the study (the central question); 2. A brief statement of what was done (methods); 3. A brief statement of what was found (results); 4. A brief statement of what was concluded (discussion, in part). Introduction: The function of an introduction is to present the question being asked and place it in the context of what is already known about the topic. In other words, this section should contain: 1. A description of the nature of the problem; 2. A statement of the purpose, scope, and general method of investigation in your study; 3. Hypothesis/ hypotheses and predictions. It is important to include some background information, but it is equally important to avoid getting lost in reviewing background information. Remember that the introduction is meant to introduce the reader to your research, not summarize and evaluate all past literature on the subject (which is the purpose of a review paper). Many of the other studies you may be tempted to discuss in your introduction are better saved for the discussion, where they become a powerful tool for comparing and interpreting your results. Include only enough background information to allow your reader to understand why you are asking the questions you are and why your hypotheses are reasonable ones. Often, a brief explanation of the theory involved is sufficient. The statement of purpose expresses the central question you are asking and thus presents the variable you are investigating. For example: This study investigates the relationship between tree density and fruit size. The purpose of this study is to determine the effect of enzyme concentration on the reaction rate of... The hypothesis is the explanation you are proposing for certain observations. It is a tentative answer to the question you have posed above. It should be accompanied by a prediction of results expected under certain conditions if the hypothesis is correct. If competition lowers reproductive output, then fruit size should be smaller when tree density increases. Write this section in the past or present tense, never in the future. Materials and methods This section should contain a description of how you tested your hypothesis, including: 1. Experimental procedures followed, with a description of the different treatments you used; A Guide to Writing Laboratory Reports 4

2. The materials and equipment (you may identify these as they are discussed, rather than listing them separately); 3. The location of the study; and 4. Any statistical techniques used. The reader should be able to reproduce your experiment after reading this section. This section is usually written in paragraph form and in the past tense. Results: The function of this section is to summarize general trends in the data without comment, bias, or interpretation. Statistical tests applied to your data are reported in this section although conclusions about your original hypotheses are saved for the discussion section. Data may be presented in figures and tables, but this does not substitute for a verbal summary of the findings. The text should be understandable by someone who has not seen your figures and tables. Example: Incorrect: the results are given in figure 1. Correct: temperature was directly proportional to metabolic rate (fig. 1). All results should be presented, including those that do not support the hypothesis. Statements made in the text must be supported by the results contained in figures and tables. Discussion: The function of this section is to analyze the data and relate them to other studies. To "analyze" means to evaluate the meaning of your results in terms of the original question or hypothesis and point out their biological significance. The discussion should contain at least: The relationship between the results and the original hypothesis, i.e., whether they support the hypothesis, or cause it to be rejected or modified. An integration of your results with those of previous studies in order to arrive at explanations for the observed phenomena. Possible explanations for unexpected results and observations, phrased as hypotheses that can be tested by realistic experimental procedures, which you should describe. Avoid redundancy between the results and the discussion section. Do not repeat detailed descriptions of the data and results in the Discussion. In some journals, results and discussions are joined in a single section, in order to permit a single integrated treatment with minimal repetition. This is more appropriate for short, simple articles (e.g., in journals such as Science or Nature) rather than for longer, more complicated ones (e.g., Journal of Experimental Marine Biology and Ecology). End the discussion with a summary of the principal points you want the reader to remember. This is also the appropriate place to propose specific further study if that will serve some purpose, but do not end with the tired cliché that "this problem needs more study." all problems in biology need more study. Do not close on what you wish you had done; rather, A Guide to Writing Laboratory Reports 5

finish by stating your conclusions and contributions. Bibliography (Literature Cited) The bibliography references should be placed in alphabetical order by author, in a special section at the end of your report. The correct style for a bibliographic entry is as follows: Last name, first and middle initial (for first author) and first and middle initial and last name (of second author); extend series for additional authors. Date (year). Title of article. Title of Journal (italics or underlined) Volume (Issue number, optional): Pages. (See the Council of Science Editors for further information.) For example: Des Jarlais, D.C. and S.R. Friedman. 1994. AIDS and the use of injected drugs. Scientific American 270(2): 82-88. Appendix An appendix (pl., appendices) includes raw data (all recorded observations), sample calculations, additional tables or figures not mentioned in the text, and any other relevant and necessary materials. Notes about tables and figures: Tables and figures should be used when they are a more efficient way to convey information than verbal description. They must be independent units, accompanied by explanatory captions that allow them to be understood by someone who has not read the text. Do not repeat in the text the information in tables and figures, but do cite them, with a summary statement when that is appropriate. Whenever possible, use a figure instead of a table. Relationships between numbers are more readily grasped when they are presented graphically, rather than as columns in a table. Tables Do not repeat information in a table that you are depicting in a graph or histogram; include a table only if it presents new information. It is easier to compare numbers by reading down a column rather than across a row. Therefore, list sets of data you want your reader to compare in vertical form. Provide each table with a number (table 1, table 2, etc.) and a title. The numbered title, and caption if appropriate, is placed above the table. Figures These comprise graphs, histograms, and illustrations, both drawings and photographs. Provide each figure with a number (fig. 1, fig. 2, etc.) and a caption that explains what the figure shows. The numbered caption is placed below the figure. Figures submitted for publication must be "photo ready," i.e., they will appear just as you submit them, or photographically reduced. Therefore, to the extent possible, figure must be produced with computer packages such as M.S. Excel. In those instances where figures must be produced by hand, lines should be drawn with black ink (not ballpoint or marker). Symbols, letters, and numerals must be produced by stencil or mechanically, and should be large enough to withstand reduction. Proportions must be the same as those of the page in the A Guide to Writing Laboratory Reports 6

journal to which the paper will be submitted. Graphs and histograms Both can be used to compare two variables. However, graphs show continuous change, whereas histograms show discrete variables only. Compare figures 1 and 2 in the appendix. You can compare groups of data by plotting two or even three lines on one graph, but avoid cluttered graphs that are hard to read, and do not plot unrelated trends on the same graph. For both graphs, and histograms, plot the independent variable on the horizontal (x) axis and the dependent variable on the vertical (y) axis. Label both axes, including units of measurement. Drawings and photographs These are used to illustrate organisms, experimental apparatus, models of structures, cellular and subcellular structure, and results of procedures like electrophoresis. Preparing such figures well is a lot of work and can be very expensive, so each figure must add enough to justify its preparation and publication, but good figures can greatly enhance a professional article, as your reading in biological journals has already shown. Things to keep in mind when writing laboratory reports: Focus on carefully obtaining, analyzing, and interpreting your results. Do not concentrate on searching for the right answer, or results that match those found by others. You should always consider the possibility that you have made an error; however, you should not reject your data just because they disagree with previously reported results. When drawing a conclusion, you must discuss and consider all of your data, not just those that support your views or hypothesis. Others may disagree with your interpretation of results, but you must consider all findings. Remember, you can never be absolutely sure that your hypothesis is true no matter how good your results may appear. Your results will almost always contain some ambiguities (some data may support and some data may refute your hypothesis). Your conclusions do not have to be completely positive or negative they may reflect a position in between. Make sure that figures, tables, or diagrams are clearly labeled, and that captions are placed correctly, an often-overlooked aspect of good communication in writing reports. Another common mistake that interferes with communication is to write too much without getting to the point. Before beginning to write, decide what is most important to say, then express yourself briefly and succinctly. For the purposes of this course you must use the passive voice and the third person ( it was found that... ). Do not wait until the last minute to write your laboratory report. First, make a detailed outline and write a draft of your report. Let it sit for a day or so, re-read it for clarity and make corrections, then write the final copy. Have a friend read your first draft and make suggestions. Always keep an extra copy of your report (and a backup copy of your computer disk) things do get lost! And turn in your report on time. You should write the abstract last, after you have first written and completed your report. Remember to keep your abstract short and precise. Excess verbiage will distract your reader from the intended purpose of your paper. A Guide to Writing Laboratory Reports 7