Writing a technical report – such as the kind required for PHYS 334 – has many key differences from writing a history report or an essay. This style guide is meant to help students learn how to appropriately and clearly communicate scientific results to their peers and will highlight both broad structure and fine details in crafting experiment reports.
The lab report is a presentation of a student’s work, both in-lab and out. It is not a list of answers to questions or a fact-dump, and it is not just the collected data or analysis. Instead, a lab report is (or should be) a cohesive narrative that tells the reader a story – why the experiment matters, how it was done, what was found, and what the results and analysis mean. The student will be graded on the quality of the experimental work, but they will also be graded on the strength of the argument presented.
Consider the data: a good lab report should detail both how and why the student collected the data, in addition to providing the numbers.
Consider the analysis: a good lab report should properly analyze the data, but it will also explain why the chosen methods are correct (e.g. motivating a particular model, or pursuing an iterative process where an initial analysis leads to new question, which lead to more data, which lead to new analysis…).
Consider the discussion: a good lab report should present a well-reasoned conclusion based on the analysis, and should describe the broader context of how this result fits into the larger sphere of physics (e.g. by comparing to other results or literature values, or by explaining how the technique, analysis, or approach could be improved).
Given the nature of experimental work, there is no such thing as a “right answer.” Instead, a student's goal for the lab report is to convince the reader that they understand both the big picture and the details, and that they have done the best they can with the data they collected.
As mentioned above, a lab report is somewhat different from a published journal article. For example, a lab report may provide more details regarding method or apparatus than an article would. Or, whereas a journal article author may simply present a plot with error bars or a final result with uncertainties, student lab report authors should also give a detailed account of how they estimated and propagated the uncertainties on those points. The student should expect their reader to know some general physics, but have no experience with the particular experiment discussed in the report.
In general, a report should include the following material (though the author may combine sections under different headings or use different titles). This list is not complete; it is meant only as a starting place and students should carefully consider what is needed for each individual experiment.
Science communication hinges on clear language. Avoid wishy-washy statements (i.e. statements that are ambiguous or which do not make a strong statement or argument), and be precise and quantitative whenever possible.
EXAMPLE: We never “measure” a photon; we measure some property of the photon (e.g its energy or frequency).
BAD EXAMPLES:
GOOD EXAMPLES:
For more information, see all the page Drawing Conclusions.
The discussion section is very important! It should not be an afterthought when writing the report. The discussion section is where you place your results in context.
Conclusions need to be quantitative whenever possible.
Avoid speculation, and instead make statements that you can justify or support
BAD:
GOOD:
GOOD:
As this is an introductory course in experimental methods, a big part of the aim is to teach good uncertainty analysis. For that reason, the graders will be especially keen to see how you estimated uncertainties, quantified statistical and systematic effects, and propagated uncertainties. You must discuss your error analysis in every report, whether it is explicitly stated in the rubric or not.
A longer discussion of uncertainty analysis can be found on the page Uncertainty Analysis and Significant Digits.
All plots included in the report should be done with python (or an equivalent high-level scripting language or software package); Excel is not a suitable program because the fitting and plotting commands are limited and do not allow users to produce professional-looking plots.
General points to keep in mind when making plots include the following:
Example plots are shown in Figs. 1 and 2.
Figures and tables should be numbered and each figure or table should have a caption which concisely describes what is shown. The caption and plot should be “stand-alone”, i.e. they should make sense when read in isolation without requiring reference to the surrounding text. (That is not to say the caption needs to be 100% complete… just that a person who flipped ahead or back in the report to a figure could reasonably understand what it shows.)
Figures and tables should be referenced in the text in the form Fig. n or Table n. When beginning the sentence with a reference to a figure, spell out the word “Figure” completely.
EXAMPLE: The fit to the data collected on Day 1 is shown in Fig. 3 and the fit parameters are listed separately in Table 1. Figure 4 shows the fit to the Day 2 data.
All numbers and uncertainty reported must include the appropriate number of significant figures.
Variables should be italicized, but numbers and mathematical symbols should not (non-italicized characters are often referred to as Roman). Descriptive subscript or superscript labels should not be italicized, unless the label includes a variable. Vectors should be bolded or marked with an overarrow. Unit vectors should be indicated by a “hat”.
Object | Examples | LaTeX |
Variables, numbers, and symbols | $a$ | a |
$B$ | B | |
$\alpha$ | \alpha | |
$3x^2 = 9\unicode[Times]{x3C0} = 9\pi$ | 3x^2 = 9\unicode[Times]{x3C0} = 9\pi | |
Labels, subscripts, and superscripts | $V_{\textrm{RMS}}$ | V_\textrm{RMS} |
$n^\textrm{(lit)}$ | n^\textrm{(lit)} | |
$\beta_\mathrm{x} \neq \beta_\mathrm{y}$ | \beta_\mathrm{$x$} \neq \beta_\mathrm{y} | |
Vectors | $\mathbf{x}$ | \mathbf{x} |
$\vec{v}$ | \vec{v} | |
$\overrightarrow{v}$ | \overrightarrow{v} | |
$\hat{z}$ | \hat{z} |
Units should not be italicized and should be separated from the number by a space. They may be abbreviated or spelled out completely. Use appropriate SI abbreviations for units. For example, Hz, not hz for hertz, and keV, not Kev or KeV for kilo-electron volts.
Correct | $x = \textrm{3.5 km}$ | x = \textrm{3.5 km} |
$\omega = 2\pi \textrm{ radians per second}$ | \omega = 2\pi \textrm{ radians per second} | |
$\omega = 2\pi \textrm{ rad/s}$ | \omega = 2\pi \textrm{ rad/s} | |
Incorrect | $x = 3.5 km$ | x = 3.5 km |
$x = \textrm{3.5KM}$ | x = \textrm{3.5KM} | |
$\omega = 2\pi \textrm{ rads per s}$ | \omega = 2\pi \textrm{ rads per s} | |
$\omega = 2\pi \textrm{ rads per s}$ | \omega = 2\pi \textrm{ rads per s} |
Reported numbers should include uncertainties and units whenever appropriate. It is always preferable to indicate the number and uncertainty together, before giving the unit, rather than list the two values separately. The preferred format is $n$ +/- $\Delta n$ or $n \pm \Delta n$
Preferred | $v = (51 \pm 3) \textrm{ m/s}$ | v = (51 \pm 3) \textrm{ m/s} |
Less Preferred | $v = 51 \textrm{ m/s} \pm 3 \textrm{ m/s}$ | v = 51 \textrm{ m/s} \pm 3 \textrm{ m/s} |
In the case of scientific notation, this same philosophy applies to grouping the prefactors together before giving the common exponent.
Correct | $v = (51.0 \pm 0.3) \times 10^{-3} \textrm{ m/s}$ | v = (51.0 \pm 0.3) \times 10^{-3} \textrm{ m/s} |
$v = 0.0510 \pm 0.0003 \textrm{ m/s}$ | v = 0.0510 \pm 0.0003 \textrm{ m/s} | |
$v = 51.0 \pm 0.3 \textrm{ mm/s}$ | v = 51.0 \pm 0.3 \textrm{ mm/s} | |
Incorrect | $v = 51.0 \times 10^{-3} \pm 0.3 \times 10^{-3} \textrm{ m/s}$ | v = 51.0 \times 10^{-3} \pm 0.3 \times 10^{-3} \textrm{ m/s} |
$v = 51.0 \times 10^{-3} \pm 3 \times 10^{-4} \textrm{ m/s}$ | v = 51.0 \times 10^{-3} \pm 3 \times 10^{-4} \textrm{ m/s} | |
$v = 0.0510 \textrm{ m/s} \pm 0.3 \textrm{ mm/s}$ | v = 0.0510 \textrm{ m/s} \pm 0.3 \textrm{ mm/s} |
Short equations and equations which will not be used later can be written inline. Longer equations and equations which will be referenced later should be placed on their own line and numbered. Equations (and single variables) should be treated just like any other word when placed within a sentence. This means that equations (and variables) should include proper punctuation before or after (if applicable) and can be placed anywhere within a sentence.
EXAMPLE: Recall that the total relativistic energy, $E$, of a particle of mass $m$ is $E = mc^2$ , where $c$ is the speed of light. On the other hand, the classical kinetic energy, $T$, of a non-relativistic particle is
$T = p^2/2m$, | (1) |
where $p$ is the particle's momentum.
When referencing an equation in the text, use the format Eq. (n). When beginning the sentence with a reference to an equation, spell out the word “Equation” completely.
EXAMPLE: We fit the data to Eq. (13) and extract the slope, $\gamma$ . Equation (14) relates $\gamma$ to the mass of the Higgs boson.
Include appropriate references (including to the lab manual or pages from the wiki) for both text and figures.
REVIEW THE UNIVERSITY PLAGIARISM GUIDELINES. We have ZERO TOLERANCE for students who plagiarize and cases WILL be referred to the Dean of Students.
Use appendices (in the same PDF document as the rest of the report) to include additional information (e.g. data or additional plots, tedious calculations, sidebar theory, etc.) without breaking the flow of the main report.
Avoid attachments and data dumps.
Provide context.
Limit how much you direct the reader to the manual for more information. If the material is key, it should be included, even if you choose to quote directly.
Abstract are short, but very important. Look over our dedicated page, Writing an Abstract, for more information.