Distribution
Error Bar Chart
Bars annotated with ± error markers — the scientific publication standard for mean ± SD or 95% CI comparisons.
Mean Reaction Time by Treatment
n=30 per group; error = 95% CI
View data (5 rows)
| Treatment | Mean | Error |
|---|---|---|
| Control | 412 | 28 |
| Drug A | 358 | 22 |
| Drug B | 290 | 35 |
| Drug C | 244 | 18 |
| Combo | 198 | 31 |
Use an error bar chart when…
- Reporting mean per group with measurement uncertainty
- Communicating confidence intervals visually
- Scientific or A/B-test results
Avoid when…
- Showing the full distribution shape (use box or violin)
- Single value with no uncertainty (use bar)
Data it needs
| Property | Value |
|---|---|
| Min Rows | 2 |
| Min Columns | 3 |
| Column Types | stringnumbernumber |
| Notes | Third column is the symmetric error magnitude (SD, SEM, or CI half-width). |
Visual anatomy
Marks
rectangleline
Channels
length-yposition-y (whiskers)
Axes
x-categoricaly-quantitative
Guiding principles
Consider instead
Common mistakes
Mixing SD, SEM, and 95% CI without labeling which
Using 1-sided whiskers when error is symmetric
History
T-shaped error bars trace to early-20th-century laboratory reports; canonized in scientific publishing.
Accessibility notes
State the error type (SD vs CI) explicitly. Provide n in the subtitle.
Related reading
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