Processing data involves calculating means, ranges and uncertainties, and expressing results with appropriate significant figures and units. Percentage uncertainty = uncertainty ÷ mean × 100; it lets you compare the quality of measurements of different sizes.
When comparing two means, consider their uncertainties. If the ranges overlap, the difference may be due to random variation rather than the independent variable. Statistical tests, used in higher-level science, help decide whether a difference is significant. Clear tables and graphs make processed data easy to check.
Worked example
A mean is 20.0 ± 0.5 s. What is the percentage uncertainty?
- Percentage uncertainty = 0.5 ÷ 20.0 × 100.
- = 0.025 × 100.
Answer:2.5%.
Key words
- percentage uncertainty
- uncertainty as a percentage of the value
- significant
- unlikely to be due to chance
- overlap
- when ranges share values
- statistical test
- a method to judge if a difference is real
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