I have a lab report
Writing a Lab Report Instructions
To write a successful scientific report you need to be clear about what you are trying to achieve. The main purpose of a scientific report is to communicate the finding from the work and to help the reader to understand them. The report should include a record of the process used to establish the findings, so they can be reproduced at a later stage for validation. It should be written as an independent record that can be read without further input from the author.
This document describes a general format for Lab Reports that you can adapt as needed.
What makes a good lab report? A good lab report does more than present data; it demonstrates the writer’s comprehension of the concepts behind the data. Merely recording the expected and observed results is not sufficient; you should also identify how and why differences occurred, explain how they affected your experiment, and show your understanding of the principles the experiment was designed to examine.
Title: A descriptive, self-explanatory title. The title must be specific and allow the reader to know exactly what you are studying.
· Bad examples:, “Choosing the best mouthwash” or “Which concentration kills more bacteria” are vague: they fail to describe what substances you used, what “best” means, how many different solutions or chemicals were tested, or what bacterial strains were used to conduct the experiment.
· Good examples: would be “The effects of three different brands of mouthwash on the growth of S. aureus.”; or “Effect of light with three different wavelengths on photosynthetic rate.”
· Great example: The main conclusion of your research is used as a title, for example, “Listerine mouthwash inhibits growth of S. aureus more effectively than Scope.”
Abstract: A concise summary of the paper’s content. This should include the question investigated/purpose of experiment, experimental design, major findings, and conclusions (significance of these findings). The abstract often also includes a brief reference to theory or methodology. The information should clearly enable readers to decide whether they need to read your whole report.
Sample Abstract:
This experiment examined the effect of line orientation and arrowhead angle on a subject’s ability to perceive line length, thereby testing the Müller-Lyer illusion. The Müller-Lyer illusion is the classic visual illustration of the effect of the surrounding on the perceived length of a line. The test was to determine the point of subjective equality by having subjects adjust line segments to equal the length of a standard line. Twenty-three subjects were tested in a repeated measures design with four different arrowhead angles and four line orientations. Each condition was tested in six randomized trials. The lines to be adjusted were tipped with outward pointing arrows of varying degrees of pointedness, whereas the standard lines had inward pointing arrows of the same degree. Results showed that line lengths were overestimated in all cases. The size of error increased with decreasing arrowhead angles. For line orientation, overestimation was greatest when the lines were horizontal. This last is contrary to our expectations. Further, the two factors functioned independently in their effects on subjects’ point of subjective equality. These results have important implications for human factors design applications such as graphical display interfaces.
The Introduction: is more narrowly focused than the abstract. It establishes the context of your experiment, including citations from primary literature.
· Background information on your system should be included
here.
· How: Select the two or three key concepts related to your experiment (usually your dependent and independent variables) and briefly explain them. For example, if your experiment involves enzymatic reactions and temperature, you should briefly describe enzymes, how they work, and what can affect their function. Then explain the consequences of changing the environmental conditions of the reaction, and finally focus on the effect of temperature.
· Clearly state your hypothesis/hypotheses and predictions.
· In the last 2 or 3 sentences of your introduction, state your hypothesis/hypotheses, which should portray the relationship you expect to find between the independent and dependent variables.
Note: Do not repeat the lab manual. Show your own comprehension of the problem.
Materials and Methods: Describe the experimental design concisely and in such a way that another researcher could re-create it.
In paragraph form, you need to explain the materials you used in the lab and also describe the experimental procedures performed to obtain your data. Use the past tense. You must be specific (give exact measurements, volumes, times, etc.), but at the same time be brief and include only details that are necessary if someone were to replicate the experiment.
Results: Summarize your data, using tables and figures (graphs) when appropriate. Only present your results here (i.e., the outcome of your experiment), save any interpretation for the Discussion
section.
This section should contain at least one paragraph (no more than 5 sentences) describing your most significant findings, followed by a graph or table that shows your data. Always refer to your table or graph in the text by citing it at the end of the sentence or using parentheses, for example “see Figure 1” or “see Table 3 below” or “(Figure 2).” Remember that your figures must have descriptive legends below them, and tables are to be identified by titles at the top. Never include raw data. Do not begin your sentences with “Figure 2 shows….” Keep in mind that you must describe the data – not the figure, graph, or table.
Notes:
If you use a calculation, provide a sample calculation in the report.
Never include raw data in your report.
The Discussion is the most important part of your report, because here, you show that you understand the experiment beyond the simple level of completing it. Explain. Analyze. Interpret.
Discussion: Interpret your results, highlighting any patterns you observed. Discuss your results in
the context of the subject of your investigation. Be sure to revisit your hypothesis and predictions
here.
In your first sentence, state whether or not the data support your hypothesis. Then interpret your results in relation to the background information. Do not repeat what you stated in the Results section; instead compare your findings to those published in the scientific literature. These may support (or not) your findings. For example, if you were testing salt concentration and its relationship to product formation in an enzymatic reaction, you should search publications in which the authors describe the effects of different salt concentrations on the enzymatic activity of similar enzymes.
Notes:
How to answer the following question: “What is the significance or meaning of the results?” To answer this question, use both aspects of discussion, a) Analysis and b) Interpretation.
a) Analysis: What do the results indicate clearly? What have you found? Explain what you know with certainty based on your results and draw conclusions:
Since none of the samples reacted to the Silver foil test, sulfide, if present at all, does not exceed a concentration of approximately 0.025 g/l. It is therefore unlikely that the water main pipe break was the result of sulfide-induced corrosion.
b) Interpretation: What is the significance of the results? What ambiguities exist? What questions might we raise? Find logical explanations for problems in the data:
Although the water samples were received on 14 August 2000, testing could not be started until 10 September 2000. It is normally desirably to test as quickly as possible after sampling in order to avoid potential sample contamination. The effect of the delay is unknown.
More particularly, focus your discussion with strategies like these:
i) Compare expected results with those obtained: If there were differences, how can you account for them? Saying “human error” implies you’re incompetent. Be specific; for example, the instruments could not measure precisely, the sample was not pure or was contaminated, or calculated values did not take account of friction.
ii) Analyze experimental error: Was it avoidable? Was it a result of equipment? If an experiment was within the tolerances, you can still account for the difference from the ideal. If the flaws result from the experimental design explain how the design might be improved.
iii) Explain your results in terms of theoretical issues: Often undergraduate labs are intended to illustrate important physical laws, such as Kirchhoff’s voltage law, or the Müller-Lyer illusion. Usually, you will have discussed these in the introduction. In this section move from the results to the theory. How well has the theory been illustrated?
iv) Relate results to your experimental objective(s): If you set out to identify an unknown metal by finding its lattice parameter and its atomic structure, you’d better know the metal and its attributes.
v) Compare your results to similar investigations: In some cases, it is legitimate to compare outcomes with classmates, not to change your answer, but to look for any anomalies between the groups and discuss those.
vi) Analyze the strengths and limitations of your experimental design: This is particularly useful if you designed the thing you’re testing (e.g. a circuit).
8. The last statement, in conclusion, simply state what you know now for sure, as a result of the lab:
Example. In conclusion, the Debye-Sherrer method identified the sample material as nickel due to the measured crystal structure (fcc) and atomic radius (approximately 0.124nm).
Literature Cited:
A list of the references you used to write your paper. If you include a reference
here, you must also cite it in-text. APA format is the correct format to use.
List the references and the sources you cited in your text following the author–year format. Include a list of your references at the end of the document. You must use the proper format for in-text citations and references. In the Literature Cited section of your report, include all authors’ last names and initials, year of publication, and full title of the paper, article, or book. For journal articles, you must list the journal name (abbreviated form is fine), volume, issue number if available, and inclusive pages. Books must be identified by publisher, place of publication, and inclusive pages.
At minimum, you should have three references: one for your background information and two for your discussion.
Format: Please use the format document on Canvas.
Make your report consistent. If your title reads “Effect of mouthwash alcohol concentration on E. coli growth,” you are stating your dependent (growth) and independent (alcohol concentration)variables. Your hypothesis should reflect that you expect these variables to interact. Your graph must have “Average diameter of growth inhibition” on the y-axis and “Alcohol concentration” on the x-axis, along with the corresponding units for these measurements or calculations in parentheses. Since concentration is a continuous variable, you should have a line graph. This is what it means to be consistent. Your narrative and research of the literature should also relate directly to these general themes.
Keep in mind that scientific writing is conventional, uses only established abbreviations, and should be clear, concise, and accurate. In addition, scientific writing uses formal language, avoids quotations, and is objective. Write with your audience in mind (college freshman level).
Reminder: 3rd person (The students/ you/ I… etc. should not be used)
