SECTION
FOUR : Discussion
Interpreting the
results of the lab
Step
1: Write a sentence or two stating whether or not the results from
the lab procedures fully support your hypothesis, do not support the hypothesis,
or support the hypothesis but with certain exceptions.
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- Go back to the
first part of your Introduction. Then
review your findings, the data from the experiment. Make a judgment
about whether or not the hypothesis has been supported. It is at this
point that you, as a scientist, must be as unbiased and objective as
possible.
- Write a sentence
stating your judgment. There are three possible judgments you can make:
- the data support
the hypothesis;
- the data do not
support the hypothesis; or
- the data generally
support the hypothesis but with certain exceptions (tell what those
exceptions are).
Example:
"The hypothesis that X solution would increase in viscosity when
solutions Y and Z were added was supported by the data."
Step
2: In a paragraph, identify specific data from your lab that led you
to either support or reject your hypothesis. Refer to the visual representations
of your data as evidence to back up your judgment about the hypothesis.
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- Return to the Results
to identify the particular data that led you to your judgment about
the hypothesis.
- Write a paragraph
(or 2 if necessary) in which you present the relevant pieces of data
from the lab and show how they relate to the hypothesis.
- Refer to data from
specific visuals appropriately: Table 1, Figure 2, etc.
Step
3: In a paragraph or two, use your understanding of the scientific
concept of this lab to explain why the results did or did not support
your hypothesis. If the hypothesis from the Introduction was not fully
supported, show how your understanding of the scientific concept has changed.
Note any citations you use here for including in the Reference section
of your report.
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In
Step 2 you pointed to data that led you to your judgment about your
hypothesis. Now you use your understanding of the scientific concept
of the lab to explain your judgment. Whatever the relationship between
the hypothesis and the results, you must provide a logical, scientific
basis for it.
- Return to the scientific
reasoning you used to generate your hypothesis (Step 2 of the Introduction).
Use it and your understanding of the scientific concept of the lab as
starting points for your explanation. Your explanation is likely to
follow one of four scenarios. Choose the one that best fits your report:
- If the results
fully support your hypothesis and your reasoning in the Introduction
was basically sound, then elaborate on your reasoning by showing
how the science behind the experiment provides an explanation for
the results.
- If the results
fully support your hypothesis but your reasoning in Introduction
was not completely sound, then explain why the initial reasoning
was not correct and provide a better reasoning.
- If the results
generally support the hypothesis but in a limited way, then describe
those limitations (if you have not already done so) and use your
reasoning as a basis for discussing why those limitations exist.
- If the results
do not support your hypothesis, then explain why not; consider (1)
problems with your understanding of the lab's scientific concept;
(2) problems with your reasoning, and/or (3) problems with the laboratory
procedure itself (if there are problems of reliability with the
lab data or if you made any changes in the lab procedure, discuss
these in detail, showing specifically how they could have affected
the results and how the uncertainties could have been eliminated).
Step
4: In a paragraph or two, restate the research question and present
the answer your experiment has suggested for that question. Show how the
experiment has helped you to solve for the unknowns.Then restate the problem
that your research was designed to solve and discuss the solution to the
problem suggested by the answer to the research question.
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At
this point in the lab report you return to where you started in the
Introduction, the problem. The goal of the lab was to answer the research
question in order to solve the problem. Now that you have presented
your data and made a judgment about your hypothesis, you are ready to
come full circle back to the problem.
- Go back to the
research question you posed in the Introduction. The experiment you
performed was designed to answer that question. If you are having trouble
starting this paragraph, here are some suggestions: “The research
question for this experiment was….”; “The experiment
described in this report was designed to answer the question,…”;
“The research reported here addressed the issue of…”.
- The research question
probably grew out of the unknowns in the problem. Answer the question
in such a way that you show a direct link between the answer and the
unknowns.
- The solution to
the problem is most likely going to center on the identification of
the unknowns. State the solution to the problem and show how the solution
to the problem came out of the identification of the unknowns.
- A good discussion
is going to enable the reader to draw a clear line from the experimental
data through the hypothesis and the answer to the research question
to the solution to the problem.
Step 5:
Discuss other items as appropriate, such as (1) any problems that occurred
or sources
of uncertainty in your lab procedure that may account for any unexpected
results; (2) how your solution to the problem compared with the solutions
of other students in the lab and an explanation for any differences; (3)
suggestions for improving the lab.
More Help:
- In science, a source
of uncertainty is anything that occurs in the laboratory that could
lead to uncertainty in your results. Sources of uncertainty can occur
at any point in the lab, from setting up the lab to analyzing data,
and they can vary from lab to lab. Return to the notes you took during
the lab procedure. Look for possible sources of uncertainty in setting
up the lab, calibrating instruments, and taking measurements as well
as problems with the materials you are using.
- In scientific articles,
the Discussion is where scientists typically compare their results to
those from other similar scientific experiments. You can do something
similar in your lab report. If you have compared your results with others
in your lab, describe what you found and comment on any differences
in the solutions to the problem: what were the differences, why there
were differences, and what are the implications of the differences for
the problem? Be sure to check with the lab instructor beforehand to
see if it is permissible to compare results. You may also draw comparisons
between your experiment and similar experiments in the topic you're
studying, as described in scientific journals. This would be a good
place to use the literature you gathered during the research phase of
your experiment.
For more advanced
labs:
- It may be useful
to classify the kinds of uncertainty you have identified. Sources of
uncertainty can be classified as random--those that cannot be predicted--or
as systematic--those that are related to personal uncertainty, procedural
uncertainty, or instrumental uncertainty.
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