Experimental data & uncertainty · SL/HL
Calibration curve
Fit standards and infer an unknown from its response.
Your values
Number formats & units
Use decimal dots in datasets. Single values also accept decimal commas and scientific notation such as 1.2e-3 or 1.2 × 10⁻³.
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Result & working
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Interpretation & assumptions
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Formula & example
The relationship
What the variables mean
| Symbol | Meaning |
|---|---|
| Fraction of response variation described by the fitted linear trend. |
Worked example
- Known concentration / amount
- 0 1 2 3 4
- Measured response
- 0.02 0.20 0.39 0.61 0.81
- Unknown response
- 0.50
- X-axis unit
- mg cm⁻³
- Y-axis label
- absorbance
2.472362 mg cm⁻³
Follow the example steps
- OLS fit: y = 0.199x + 0.008
- R² = 0.9987138
- x_unknown = (y_unknown − c)/m = (0.5 − (0.008))/0.199 = 2.472362 mg cm⁻³
Common mistakes
Use the intercept when converting a response to a concentration.
Incorrect approach
y = 2x + 1, y = 5: x = 5/2 = 2.5
Correct approach
x = (5 − 1)/2 = 2
More checks before you submit
- Do not assume a high R² proves the method has no systematic bias.
Method notes
Common in colorimetry and other biological assays. The unknown is most defensible within the calibrated range.