Spring 2011 Writing a lab report for 4410/6510


Spring 2011 Writing a lab report for 4410/6510

Writing a lab report for 4410/6510

Spring 2011

Includes material from D. Hartill and others

Purpose of publication in science

• The report communicates the results of your

experiment to your colleagues

• In the research world, the paper that you write about

the results of your experiments provides the public

record of what happened to the money from your grant

• The paper will also have an important influence on the

outcome of future proposals for support of your


• Finally and probably the most important, the paper

establishes your “ownership” of the experimental



Requirement: three lab reports

• Each lab is completed when you hand in a lab report

• The lab report has several functions

–It documents your work

–It allows you to communicate your results to others

(colleagues, instructors)

–It is a crutch to allow you to frame your work in a

coherent whole

• “If you haven’t published it, it didn’t happen.”


What should be in the lab report

• Modeled on a Physical Review Letter (PRL)

–http://prl.aps.org; look up your favorite topic and download

and read one (off-campus might require a subscription)

–Roughly 5-10 page double-spaced document

–Should describe your result completely, from what you did

to the relevance and connection to other results in the wider


–Standalone, self-contained document

• Goal is to get some practice writing a paper like a real

scientific paper

–PRL: prestigious journal of the American Physical Society


Table of Contents (Approximate page counts)

• Abstract (one paragraph summary of results)

• Introduction (1/2 to 1 page)

• Theoretical Background (1 page)

• Description of the Apparatus (1 page with diagram)

• Data (1 page of summary tables or graphs of your data)

• Analysis (the meat of the report - 2 to 3 pages of sample

calculations, graphs, fits to the data, etc.)

• Quantitative uncertainty assessment (1 page including


• Conclusions (1 page summary of results and comparison to

previous experiments)

• References

• Appendices (optional: inclusion of extra data, analysis programs,

etc.) 6


• You must include references your sources and include


• Wikipedia is not sufficient for most material: reference

(and read) original sources

• Copy-paste is never acceptable


Example Abstract (E-4, Stern Gerlach)

• Problem: No numerical results mentioned in abstract.

Should stand alone (will be only thing some people

read) and communicate results succinctly

• Abstracts are your (only) chance to hook people into

reading your paper


Example Introduction (N-17, µ lifetime)

• Context of the measurement in broader setting.

Historical background, if appropriate.

• Not too long (what is shown is not complete … )

• Nice introduction.


Example theory section (E-4, Stern-Gerlach)

• Cribbed directly from Wikipedia

• No attribution! (not a real example.)


Example Apparatus (S-10, optical pumping in Rb)

• Nice schematic view. Does not have to be fancy. Lab

writeup is fair game (with attribution!)


Example data plot (Stern Gerlach)

• Problems:

– Too small

– No error bars

– no units, missing y axis label

– caption is incomplete and


• Good

– Use of color 12

Example conclusion (O-2, diffraction)

• Vague. “… could be improved with appropriate experimental …”

• Conclusion State result clearly and succinctly. “Using technique

A, we measured x ± y ….” 13

Common Pitfalls

• Trying to include too much in the report

• Uncertainty analysis by quoting the uncertainty in your measurement

as the difference between your result and the accepted value for the

parameter that you had measured - this is my least favorite mistake

• Copying a long theoretical treatment from a book ...

– Try to only include the pertinent background comments and formulae.

• … and then not properly referencing it.

– Properly reference outside sources

• Forgetting to include error bars on the graphs

• Omitting an appropriate diagram of the apparatus

• Too many detailed diagrams of the circuits, layout, pictures, etc of

the apparatus

• Including material that has little to do with the experiment that you

have carried out

• Twenty page long report ← THIS IS THE WORST (for us☺)


Some advice

• Figures are the most important part of a paper.

– Make them clear, attractive, and properly labeled. Use descriptive figure

captions, properly numbered. Graphs should always include error bars

on the data points

Writing a good report takes time

– Starting the analysis the night before is not a successful strategy

– All too often, a key piece of data or a parameter from the apparatus is

missing and there is no time to obtain it

– Experience from many of your colleagues is that starting the analysis

while you are taking the data is a very useful strategy

• Begin writing the report as you are carrying out the final analysis

– In writing you will have to bring it all together to produce a coherent repot

– Let the report sit for a day, reread it and then correct its shortcomings

• The primary goal of the report is not to compare to previous value.

– It is to report on the experiment you did and estimate the accuracy of the



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