--- title: "Writing Science: the Figure, the Error Bar and the Claim" description: "Report a measured estimate with units and defined uncertainty. Present figures and captions that state only what the evidence supports. Identify statistical and systematic contributions and describe t" canonical: https://lightmysky.com/learn/science/writing-science-the-figure-the-error-bar-and-the-claim-mt_uUQ4gKXTN0 source: https://lightmysky.com/learn/science/writing-science-the-figure-the-error-bar-and-the-claim-mt_uUQ4gKXTN0.md retrieved: 2026-11-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Writing Science: the Figure, the Error Bar and the Claim Report a measured estimate with units and defined uncertainty. Present figures and captions that state only what the evidence supports. Identify statistical and systematic contributions and describe the method so another group can repeat the procedure and check the analysis. Subject: Science · Area: Scientific Inquiry · Ages 23 to 24 Page: https://lightmysky.com/learn/science/writing-science-the-figure-the-error-bar-and-the-claim-mt_uUQ4gKXTN0 ## Ready when they can - Drafts a figure whose caption states the claim it supports - Reports a result with statistical and systematic uncertainties kept separate - Writes a method description detailed enough for another group to repeat ## Lesson: Writing a result others can check Report a measured estimate with its unit and an uncertainty whose meaning is defined. Exact counts need no measurement uncertainty. Accuracy concerns agreement with a reference; precision concerns agreement among repeats. Three scale readings of 183 g agree with each other but miss a 180 g reference. Correct known offsets where appropriate and include uncertainty in the correction. With independent readings under stable conditions, more data can reduce statistical uncertainty in the mean. Averaging does not narrow the underlying spread of individual readings or remove a shared fixed offset. Report statistical and systematic contributions separately by source. You may also give a total uncertainty if you explain the combination method and correlations. Better calibration or design can reduce systematic uncertainty. **Example.** State your rounding convention. Here, round uncertainty to one significant digit, then the estimate to the same decimal place. An estimate of 6.283 s with uncertainty 0.047 s becomes 6.28 ± 0.05 s. Some conventions retain two significant digits in uncertainty. Keep extra working digits during calculations and round the reported result at the end. Name plotted variables and give their units. Add a legend when groups or markers need identifying. Define error bars: they might show spread, standard uncertainty or a confidence interval. Give a confidence level when applicable. Show uncertainty where readers need it to judge the finding. Make axis limits clear and consider their effect on interpretation; a nonzero axis is not automatically misleading. A caption identifies the measurement, groups or sample size, and the supported finding. State its limits. If an observational sample shows two variables rising together, describe an association in that sample. Association alone does not establish that one variable caused the other to change. Other causes may explain the pattern. Document instruments, settings, calibration and sample sizes. State exclusions and when their rules were chosen. Give analysis steps or accessible code with versions. Define symbols, give units and provide access to data needed to check reported numbers. Another group should be able to repeat the procedure, without an identical estimate being guaranteed. Before calling estimates contradictory, compare uncertainty definitions, conditions, calibration and analysis. **Recap.** Define the estimate and uncertainty, make the figure interpretable, limit claims to their evidence, and document how the result can be checked. *Lesson, questions and flashcards written for this dataset. Supplied OpenStax measurement and units sections informed factual and teaching-design study; their prose was not reused.* ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Reading a Paper: the Claim, the Evidence and the Assumption](https://lightmysky.com/learn/science/reading-a-paper-the-claim-the-evidence-and-the-assumption-mt_YFgMvbohC0) ## Optional connections - [Writing Science Reports](https://lightmysky.com/learn/science/writing-science-reports-mt_ThTbUuNb3p)