Writing Lab Reports and Scientific Papers
Verbal communication is temporal and easily forgotten, but written reports exist for long periods and yield long-term benefits for the author and others. Scientific research is a group activity. Individual scientists perform experiments to test hypotheses about biological phenomena. After experiments are completed and duplicated, researchers attempt to persuade others to accept or reject their hypotheses by presenting the data and their interpretations.
The lab report or the scientific paper is the vehicle of persuasion; when it is published, it is available to other scientists for review. If the results stand up to criticism, they become part of the accepted body of scientific knowledge unless later disproved.
In some cases, a report may not be persuasive in nature but instead is an archival record for future generations. For example, data on the distribution and frequency of rabid skunks in a certain year may be of use to future epidemiologists in deciding whether the incidence of rabies is increasing. Regardless of whether a report is persuasive or archival, the following guidelines apply.
FORMAT
A scientific report usually consists of the following:
1. Title
2. Abstract
3. Introduction
4. Materials and methods
5. Results
6. Discussion
7. Literature cited
There is general agreement among scientists that each section of the report should contain specific types of information.
TITLE
The title should be less than ten words and should reflect the factual content of the paper. Scientific titles are not designed to catch the reader’s fancy. A good title is straightforward and uses keywords that researchers in a particular field will recognize.
ABSTRACT
The purpose of an abstract is to allow the reader to judge whether it would serve his or her purposes to read the entire report. A good abstract is a concise (100 words) summary of the purpose of the report, the data presented, and the author’s major conclusions.
INTRODUCTION
The introduction defines the subject of the report. It must outline the scientific purpose(s) or objective(s) for the research performed and give the reader sufficient background to understand the rest of the report. Care should be taken to limit the background to whatever is pertinent to the experiment. A good introduction will answer several questions, including the following:
Why was this study performed?
Answers to this question may be derived from observations of nature or from the literature.
What knowledge already exists about this subject?
The answer to this question must review the literature, showing the historical development of an idea and including the confirmations, conflicts, and gaps in existing knowledge.
What is the specific purpose of the study?
The specific hypotheses and experimental design pertinent to investigating the topic should be described.
MATERIALS AND METHODS
As the name implies, the materials and methods used in the experiments should be reported in this section. The difficulty in writing this section is to provide enough detail for the reader to understand the experiment without overwhelming him or her. When procedures from a lab book or another report are followed exactly, simply cite the work, noting that details can be found in that particular source. However, it is still necessary to describe special pieces of equipment and the general theory of the assays used. This can usually be done in a short paragraph, possibly along with a drawing of the experimental apparatus. Generally, this section attempts to answer the following questions:
What materials were used?
How were they used?
Where and when was the work done? (This question is most important in field studies.)
RESULTS
The results section should summarize the data from the experiments without discussing their implications. The data should be organized into tables, figures, graphs, photographs, and so on. But data included in a table should not be duplicated in a figure or graph.
All figures and tables should have descriptive titles and should include a legend explaining any symbols, abbreviations, or special methods used. Figures and tables should be numbered separately and should be referred to in the text by number, for example:
1. Figure 1 shows that the activity decreased after five minutes.
2. The activity decreased after five minutes (fig. 1).
Figures and tables should be self-explanatory; that is, the reader should be able to understand them without referring to the text. All columns and rows in tables and axes in figures should be labeled. See appendix B for graphing instructions.
This section of your report should concentrate on general trends and differences and not on trivial details. Many authors organize and write the results section before the rest of the report.
DISCUSSION
This section should not just be a restatement of the results but should emphasize interpretation of the data, relating them to existing theory and knowledge. Speculation is appropriate, if it is so identified. Suggestions for the improvement of techniques or experimental design may also be included here. In writing this section, you should explain the logic that allows you to accept or reject your original hypotheses. You should also be able to suggest future experiments that might clarify areas of doubt in your results.
LITERATURE CITED
This section lists all articles or books cited in your report. It is not the same as a bibliography, which simply lists references regardless of whether they were cited in the paper. The listing should be alphabetized by the last names of the authors. Different journals require different formats for citing literature. The format that includes the most information is given in the following examples:
For articles:
Fox, J.W. 1988. Nest-building behavior of the catbird, Dumetellacarolinensis. Journal of Ecology 47: 113-17.
For Books:
Bird, W.Z. 1990. Ecological aspects of fox reproduction. Berlin: Guttenberg Press.
For chapters in books:
Smith, C.J. 1989. Basal cell carcinomas. In Histological aspects of cancer, ed. C.D. Wilfred, pp. 278-91. Boston: Medical Press.
When citing references in the text, do not use footnotes; instead, refer to articles by the author’s name and the date the paper was published. For example:
1. Fox in 1988 investigated the hormones on the nest-building behavior of catbirds.
2. Hormones are known to influence the nest-building behavior of catbirds (Fox, 1988).
When citing papers that have two authors, both names must be listed. When three or more authors are involved, the Latin et al. (et alia) meaning “and others” may be used. A paper by Smith, Lynch, Merrill, and Beam published in 1989 would be cited in the text as:
Smith et al. (1989) have shown that…
This short form is for text use only. In the Literature Cited, all names would be listed, usually last name preceding initials.
There are a number of style manuals that provide detailed directions for writing scientific papers.
GENERAL COMMENTS ON STYLE
1. All scientific names (genus and species) must be italicized. (Underlining indicates italics in a typed paper.)
2. Use the metric system of measurements. Abbreviations of units are used without a following period.
3. Be aware that the word data is plural while datum is singular. This affects the choice of a correct verb. The word species is used both as a singular and as a plural.
4. Numbers should be written as numerals when they are greater than ten or when they are associated with measurements; for example, 6 mm or 2 g but two explanations of six factors. When one list includes numbers over and under ten, all numbers in the list may be expressed as numerals; for example, 17 sunfish, 13 bass, and 2 trout. Never start a sentence with numerals. Spell all numbers beginning sentences.
5. Be sure to divide paragraphs correctly and to use starting and ending sentences that indicate the purpose of the paragraph. A report or a section of a report should not be one long paragraph.
6. Every sentence must have a subject and a verb.
7. Avoid using the first person, I or we, in writing. Keep your writing impersonal, in the third person. Instead of saying, “We weighed the frogs and put them in a glass jar,” write, “The frogs were weighed and put in a glass jar.”
8. Avoid the use of slang and the overuse of contractions.
9. Be consistent in the use of tense throughout a paragraph–do not switch between past and present. It is best to use past tense.
10. Be sure that pronouns refer to antecedents. For example, in the statement, “Sometimes cecropia caterpillars are in cherry trees but they are hard to find,” does “they” refer to caterpillars or trees?
After writing a report, read it over, watching especially for lack of precision and for ambiguity. Each sentence should present a clear message. The following examples illustrate lack of precision:
1. “The sample was incubated in mixture A minus B plus C.” Does the mixture lack both B and C or lack B and contain C?
2. The title “Protection against Carcinogenesis by Antioxidants” leaves the reader wondering whether antioxidants protect from or cause cancer.
The only way to prevent such errors is to read and think about what you write. Learn to reread and edit your work.
BHCC
Env Sci 105
Prof. Frashure
Systems Lab
A Simple Computer Model
of a Simple Ecosystem
(Chapter3)
Introduction
Chapters 1 and 3 from your textbook discuss models and simple systems. In this experiment you will interact with a simple ecosystem model. There are only three organisms in this system: wolves, rabbits and grass. Based on mathematical formulas and probability of certain events occurring, the model predicts the changes in the populations of the three organisms. You will be able to change different variables, such as the starting number of organisms, the reproduction rate, the food consumption rate, the growth rate etc… Hopefully, this model will illuminate a few things for you: first you will see how connected things are within an ecosystem; second, you will see how small changes in one organism can influence the rest of the system; third, you will get some ideas about how computer models can be helpful to environmental scientist and lastly, how difficult it is for a human to make even a simple ecosystem function properly.
Since this is your first lab, I have provided you with objectives (things you are trying to accomplish by doing this lab). In later labs you will have to come up with and write your own objectives as part of your lab report.
Objectives
1. To view and interact with a simple scientific computer model.
2. To determine how simple changes in populations of one organism will effect
populations of organisms in the same system.
3. To use a computer model to complete objective 2.
Getting started:
Grass, Rabbits and Wolves – a computer model. For this lab assignment you will be running a simple computer simulation of a forest ecosystem that is comprised of wolves, rabbits and vegetation.
The simulation program is found at www.shodor.org/interactivate/activities/index.html. Move to the bottom of this page and you will see an activity called “Rabbits and Wolves” Click on that line to open up the simulation experiment. Read the “What?” “How?” bars at the top of the page. They help explain how the simulation works. In this simulation you have rabbits that each plants and wolves that eat rabbits. You can control different factors such as the population of each organism, growth rate of the plants, the food consumption rate of the animals and many others. First, just learn how to run the program and see the graphs and statistics after the simulation runs through. Use the “cumulative statistics” bar to stop the simulation. Click the “population graph” bar and you will see a graph that shows the growth and decline for the three organisms (wolves, rabbits and grass). Keep this graph open while you run the simulation, you will see the populations change over time. Look at the bottom of this graph it says “iteration”- this is a time factor in the model, you can think of it as a generation. You will be running the simulation a few times. Each time you run the simulation let it progress through at least 200 iterations. Play around – manipulating the different variables under the tab called “view/modify the parameters”. Once you are familiar with how the program works you can start your lab assignment.
Record the start-up parameters for each run at the beginning of the simulation and cumulative statistics at the end of each run. You will need to record the graphs created by the program for your results section. You can copy the graphs and past them into your lab report using the following procedure: After running a simulation, pause the model. Then click on the graph to make it the active window. To take a screenshot in Mac OS X, you can press Command + Shift + 4 and drag a box around the screen portion you wish to capture. The screenshot will be saved onto the desktop. Drag the screen shot into your laboratory report.
Procedure
Run 1 – Run the starting simulation with the default or starting parameters. Run for 200 iterations (you see the number of iterations when you open the population graph). Record the “cumulative statistics”, and describe the lines on the population graph for each of the three organisms (rabbit, wolf, grass) (if you know how to do a “print screen” then copy the graph to a word processingdocument so you can include it in your report.. This is RUN 1. Run the simulation three more times changing the variables as noted below:
Run 2 – start with 0 wolves (change the start up parameters). Run for 200 iteration. Record the cumulative statistics and copy the graph if you can.
Run 3 – cut the grass value in half. Run for 200 iterations. Record the cumulative statistics and copy the graph if you can.
Run 4 – your option. Change any parameters you wish. Record your parameter changes and let the program run for 200 iterations. The goal for Run 4 is to have all three organisms living at the end of 200 iterations. Try at least 10 different Run and record the cumulative statistics and copy the graph of your best Run.
After each run (for 200 iterations) record the “cumulative statistics” and write a brief describe the population growth curve for each organism. These will be put into a table for your results section.
For your write-up please include the following:
Results Section:
You should have three sets of data for each run: (1) Prior to each run, record the start-up parameters; 2) At the end of each run copy/paste the graph; and 3) At the end of each run record the cumulative statistics. These should be pasted into your report using the procedures mentioned earlier. Label each table and graph. Table 1. Start-up Parameters for Run 1, Graph 1 for Run 1, Table 2. Cumulative Statistics for Run 1 and so on.
Paste your results here:
Results for Run 1.
Table 1a. Start-up Parameters for Run 1
Graph 1. Results for Run 1
Table 1b. Cumulative Statistics for Run 1
Results for Run 2.
Table 2a. Start-up Parameters for Run 2
Graph 2. Results for Run 2
Table 2b. Cumulative Statistics for Run 2
Results for Run 3.
Table 3a. Start-up Parameters for Run 3
Graph 3. Results for Run 3
Table 3b. Cumulative Statistics for Run 3
Results for Run 4 (record your best results even if every species only lived for less than 200 years).
Table 4a. Start-up Parameters for Run 4
Graph 4. Results for Run 4
Table 4b. Cumulative Statistics for Run 4
Discussion Section (incorporate your answers into the discussion section of the lab report)
For your discussion section on the lab report (each question should include supporting research and data. Your answers for each question should be at least one paragraph long.
1 – Discuss the changes in parameters for each run and how they affected the population growth curves for each organism (be sure to mention particular changes in the graphs and
ending populations). Include a description of how the population changes (the graphlines) occurred throughout the run is necessary.
2 – Think about how this simulation could apply to the real world ecosystem. What other factors or variables would have to be included.
3 – What if humans were added as a fourth organism, how would they affect this?
simulation (wolves, rabbits, and grass).
4. Also, do you think that a computer model is a useful tool to science? More precisely do you think there are times when such a model is useful and when?
such a model is not useful?
5. Be sure to start your discussion with a statement of objectives for this lab:
Objectives
a. To view and interact with a simple scientific computer model.
b. To determine how simple changes in populations of one organism will effect
populations of organisms in the same system.
c. To use a computer model to complete objective 2.
Write and state if you think you obtained the objectives and explain why or why not. There is absolutely no penalty for thinking that you didn’t complete one of the objectives.
