How to write a lab report
APES
Instructions on writing a Lab Report
Major points to be aware of for lab reports (mistakes often made)
•
If your data don’t support your hypothesis, they are not “wrong” or “flawed”. This
means you cannot reject your null hypothesis. Believe your data, and interpret their
meaning even if they aren’t what you expected.
•
Results sections always have text in addition to tables and figures. The text does not
repeat what’s in the tables and figures – it summarizes the important points. The idea is to
save your reader the time from having to interpret the data themselves. Do it for them. Tell
them what they should “get” out of the data.
•
The Introduction and Discussion sections should both address the importance and
relevance of your experiments. Why were they done? What questions were you
addressing? Why should anyone care about these experiments? What do the results
mean? Always have the “Big Picture” in mind. Don’t make your reader guess about the
importance of your experiments – tell them! These sections should also cite other
published papers, to compare what your results suggest to what others have found.
•
The Results section should present your data in some kind of synthesized way. Raw
data may not be necessary; graphs, diagrams, and tables can be much more helpful. Basic
statistical analyses can be much easier to interpret, even something as simple as showing
means and standard deviations rather than just raw data (which makes the reader have to
work to figure out what your data mean). When graphing means, always include error bars
that show standard deviations. Seeing the variance in data is at least as important as
seeing the means!!!
•
Hypotheses are never “proved”, only disproved. The language to use is to say the data
either “supported” or “did not support” your hypothesis. Even if your data support your
hypothesis, there is always the possibility you did not measure something critical, so your
results could be interpreted another way. However, if your data don’t support your
hypothesis, you can then say “the null hypothesis cannot be rejected”.
•
Cite sources properly in the text and in the Literature Cited sections. See the guidelines
and examples below, but also consult the IMC website.
Papers
with this
many
authors…
At the end of the information
concerning the paper
Within the sentence
1
(Einstein, 1930 )
.. as stated by Einstein (1930), there is no
chance…
2
(Tesla and Westinghouse, 1890)
… as stated by Tesla and Westinghouse
(1890), there is no chance…
3 or more
(Darwin et al., 1860)
… as stated by Darwin and others (1860),
there is no chance…
Cite it one of these two ways in the text
How to write a lab report
APES
How these papers look in the text
Example 1: citations at the end of phrases or sentences
Einstein moved to New Jersey in the 1930s as Hitler rose to power in Germany; he always
said that Princeton was a really nice place to live (Einstein, 1930). Living at a time of rapid
modernization, Einstein was eternally grateful for commercial electricity, and agreed with its
developers that alternating current was the best way to deliver electricity across long distances
(Tesla and Westinghouse, 1890). While he was making important contributions to theoretical
physics, evolutionary biologists were developing the modern synthesis, bringing together the
theory of evolution by natural selection (Darwin et al., 1860) with Mendelian genetics.
Example 2: citations embedded within the sentences
Princeton was a really nice place to live, according to Einstein (1930), who moved there in
the 1930s as Hitler rose to power in Germany. Living at a time of rapid modernization, he was
eternally grateful for the contributions of Tesla and Westinghouse (1890) to the development of
alternating current as the standard of electricity delivery. While Einstein was making important
contributions to theoretical physics, evolutionary biologists were developing the modern synthesis,
bringing together the ideas of Darwin, Wallace, and Bates (1860) with Mendelian genetics.
How these papers look in the Literature Cited section
Darwin, C., Wallace, A.R., and Bates, H. 1860. You won’t believe what we went through to bring
you the theory of evolution by natural selection. Journal of Weary World Travellers 2: 6-12.
Einstein, A. 1930. Life as a German-American scientist in Princeton. New Jersey Digest 1: 1-10.
Tesla, N. and Westinghouse, G.. 1890. On why alternating current is the way to deliver
commercial electricity. Electricity Today 5: 100-105.
Basics of scientific writing style

Accurate, clear, and concise writing is essential to effective communication. Be direct in your
writing, and be careful that everything in the lab report is important and relevant to the
question or hypothesis.

I will accept papers written in the passive voice if that’s what you’ve learned in other science
classes, but in the scientific journals I read, the active voice and first person are used. So,
you will not be penalized for using the passive voice, but I will encourage you to use the first
person (“I” or “we”) and the active voice instead of the passive voice (“I measured the water
temperature” instead of “The water temperature was measured”) if you are comfortable with
doing so.

Avoid repeating facts or ideas. Decide which section of the lab report each piece of information
belongs in, and do not repeat it unnecessarily.

Be concise and succinct. Include everything that is necessary; don’t “pad” the paper with
anything irrelevant.

Data is plural; datum is singular!!!
How to write a lab report
APES
What sections to include, and what to put in each one
Introduction
o
o
o
Make sure to relate the experiment to the “Big Picture”
Describe what is already known about your topic, and what others have done and found,
citing the primary and secondary scientific literature to back up what you write
At the end of this section, formally state your hypothesis, after giving enough background
information and explanation so it makes sense and seems obvious to your reader
This section should contain the general objectives of the study and the specific hypothesis
or hypotheses tested. The significance of those objectives and/or their relation to the “Big Picture”
(a more general question or issue) should be explained in this section. Any other background
information necessary for the reader to grasp the purpose or relevance of the study should be
provided in this section, such as what others have done; you should always cite the sources of
your information and put the full citations in the Literature Cited section as well. In summary, this
section should present the objectives, justification, and background of your study, and should use
other papers to support the background information found here.
Methods
o
o
This section is not to be written as a list or a step-by-step protocol. It should have full
sentences and read like normal text.
Someone new to your experiment should have all the information in this section that they’d
need to repeat your experiment if they wanted to.
This portion of your report should consist of a detailed description of what was done and
how it was done, including any equipment used (but do NOT list separately the “materials”
employed). The description should be detailed enough that a reader could duplicate your
investigative procedure, but should not include any unnecessary details (e.g. whether data were
recorded with a pen or a pencil; just say “we recorded the data”) nor detailed description of
standard procedures (e.g. how an item was weighed; just say “we weighed the item”).
Results
o
Show statistics (e.g. means and standard deviations) in this section; not raw data
o
Summarize data in tables and graphs
o
Tables and graphs should have legends: text that goes with each one, giving it a name (e.g.
“Figure 1”) and saying what the data are that are in the table or figure (see examples)
o
Include text in the Results section that tells the reader what trends, patterns, and
interesting data points you see in your results.
o
Do not explain your data here; just show them clearly and point out trends.
o
If appropriate, do a statistical test on your data, and include an interpretive statement that
tells the reader what the statistical test results show, without explaining why you got
those results (that goes in the Discussion)
o
Figures can be graphs, photos, or drawings. Tables are organized data lists.
How to write a lab report
APES
Here you present the data derived from the study, as well as describes any trends,
patterns, or relationships which can be seen in those data. Listings of raw data are usually not
given, except occasionally as an appendix to the report. Usually, data are presented in some
summarized form, usually descriptive statistics (e.g. means, standard deviations, frequencies,
percentages, etc.). Data summaries may be presented as tables and/or figures, if this helps to
illustrate a trend or results in greater clarity.
Below are two examples clear graphs with
figure legends. Note the information in the figure
legends, and the variability shown as error bars in
both figures. (Figure 1: from Cleveland et al., 2010 (Ecology
91(8): 2313-2323); Figure 3: from Gilchrist et al., 2001 (Genetica
112-113: 273-286)).
How to write a lab report
APES
And here is an example of a clear table with a table legend, taken from Cleveland et al.,
2010 (Ecology 91(8): 2313-2323). Note how the table legend tells you that the values in the table
are means ± standard deviations (SD).
The results section should consist, however, of more than a collection of tables, graphs, or
other data summaries; it should contain descriptions of the patterns, trends, and relationships
which you observed. For example, for Figure 3 above, do not just say “The wing size of Drosophila
relative to latitude is shown in Figure 3”; describe the trends you observed in the data and tell the
reader where they can observe this trend, such as in “The wing size of Drosophila increased with
latitude in European species” (Figure 3)”.
Graphs, diagrams, and photographs that visually depict your results are all referred to as
figures and are individually numbered. Tables of data are referred to as tables and are
individually numbered in a series separate from the figures. Each figure and table should be cited
at least once in the text by its respective number. Each figure and table should have an
explanatory title or legend. If a graph will summarize the data as well as or better than a table,
then a graph is preferable. For both tables and graphs, be sure that the units of measurement and
what was measured are obvious for all numbers given (e.g. 2000 kg of elephant, 550 kcals of
cream puff, etc.). Use metric units of measure wherever possible. The axes of all graphs should
be correctly and thoroughly labeled with what was measured and the units of measure. Each axis
should be marked with a scale.
Discussion and Conclusions
o
Do not rehash results here; only discuss overall trends or interesting points from the results
(i.e. don’t go through the results one by one)
o
Make sure you relate your results to your hypothesis. Did they support or not support your
hypothesis? Can you reject or not reject the null hypothesis?
o
Describe what others have done, citing those sources, and comparing others’ results to
your own. Use sources that help explain your data and enhance your reader’s
understanding of what your results mean.
o
Relate your experiment and results to the “Big Picture”. What does it all mean beyond your
specific experiment? Why should your reader care? Make your experiment and
hypothesis relevant, by putting everything into a greater context.
How to write a lab report
APES
The patterns described in the Results section are interpreted and critically evaluated in
this section. Conclusions are then drawn on the basis of this interpretation and evaluation of the
validity of the results. In your critical evaluation of the results, discuss the amount and possible
sources of variability in your data. Also, discuss any possible sources of bias or other errors, and
give an evaluation of the impact of these sources on interpreting the results of the study.
Be sure to include somewhere an explicit statement as to whether the hypothesis or
hypotheses were supported or refuted by the results. Be sure you make clear the bases for all
your interpretations and conclusions; present an “argument” for each which is based explicitly on
your findings. Include any other conclusions that you can derive from your study, as well as the
study’s relationship to any other studies, in this part of the report.
Literature cited
The references below show a format for citing a paper published in a scientific journal and
for a book citation; the journal article cited gives the volume and page numbers at the end of the
citation. Use the resources at the IMC website to help.
Journal article:
Smith, J.A. 1900. Who cares about Cassiopeia anyway? Journal of Unnecessary Knowledge
3:10-15
Book
Smith, J.A. 1901. Why temperature affects Cassiopeia. Rowan Biology Press, Glassboro, NJ,
USA
The order of writing vs. presenting sections in a
scientific paper
Order
As presented in the
completed paper…
But write the sections
in this order
1
2
3
4
5
6
7
Abstract
Introduction
Materials & Methods
Results
Discussion
Acknowledgements
Literature Cited
Results
Methods
Discussion
Introduction
Abstract
Literature Cited
Acknowledgements
How to write a lab report
APES
Whenever writing a lab report, ask yourself these ten questions
1. Have I completely understood what I have done, read, or been told?
2. Are my notes accurate and do they distinguish between my thoughts and words and those
of the author(s)
3. Does my opening paragraph prepare the reader for all that follows?
4. Does my writing flow smoothly and logically from point to point? Are there adequate
transitions between sentences and paragraphs?
5. Does each sentence make its case completely, concisely, and unambiguously?
6. Is every fact or opinion supported with a reference, example, or explanation?
7. Have I proofread and revised for spelling, grammatical, and typographical errors?
8. Are my graphs equipped with clearly labeled axes (including units) and sufficiently detailed
explanatory captions? Are my tables equipped with suitable column headings
(including units) and captions?
9. Are all numbers followed by their units?
10. Does the title of my paper or report reflect its content?
Most writing style and tips are from:
Pechenik, J.A. 1987. A short guide to writing about biology. Little, Brown, and Company.Boston,
MA, USA