Meaning & use
confidence interval
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Meaning
nouncountabletechnicalmathematics
A range of values calculated from sample data that is likely to contain the true value for the whole population.
Grammar: Countable: use 'a confidence interval' or 'confidence intervals'; often followed by 'for' or 'around'.
Patterns
- a confidence interval for something
- a 95% confidence interval
- calculate a confidence interval
The researchers reported a 95% confidence interval for the average height of adult men in the city.
A wider confidence interval means the estimate is less precise.
The poll's confidence interval was plus or minus three percentage points.
Word forms
| plural | confidence intervals |
|---|
Common combinations
- 95% confidence interval
- The 95% confidence interval for the mean score was 60 to 70.
- calculate a confidence interval
- You can calculate a confidence interval from the sample mean and standard deviation.
- wide confidence interval
- The small sample size produced a wide confidence interval.
- narrow confidence interval
- With more data, the confidence interval became narrower.
- confidence interval for the mean
- The confidence interval for the mean was 4.2 to 5.8.
Synonyms and how they differ
- interval estimate
- A more general term for any range used to estimate a population value; 'confidence interval' specifies the level of confidence.
- margin of error
- Often used in polls to mean the half-width of a confidence interval, not the whole range.
Word family
- confidence level noun
- The probability (e.g., 95%) that the interval contains the true value.
- confidence limit noun
- Either end of a confidence interval.
Commonly confused: confidence interval or credible interval?
confidence interval vs credible interval
A Bayesian term similar in spirit but based on a posterior distribution, not frequentist sampling.
Practice
In the sentence 'The study reported a 95% confidence interval of 10 to 20', what does the interval 10 to 20 represent?
Choose one answer.
A confidence interval gives a range that is likely to contain the true population value, not the exact value or a probability for a single number.
Make it your own
Write a sentence using “confidence interval”, then check it and compare it with the examples above.