confidence interval: meaning, definition, pronunciation and examples
C1/C2 (Academic/Professional)Formal, Academic, Technical (Statistics, Research, Science, Medicine)
Quick answer
What does “confidence interval” mean?
A range of values, derived from a sample, that is likely to contain the true value of an unknown population parameter with a specified level of probability (confidence level).
Audio
Pronunciation
Definition
Meaning and Definition
A range of values, derived from a sample, that is likely to contain the true value of an unknown population parameter with a specified level of probability (confidence level).
In everyday language, it represents a statistical 'margin of error' or the precision of an estimate, acknowledging uncertainty rather than providing a single exact figure.
Dialectal Variation
British vs American Usage
Differences
No significant lexical differences. The concept and term are identical. Minor potential differences in phrasing, e.g., 'at the 95% level' (common everywhere) vs. 'with 95% confidence' (also common everywhere).
Connotations
Identical technical connotations. In public discourse (e.g., news), both UK and US media often simplify it to 'margin of error.'
Frequency
Equally high frequency in academic and research contexts in both varieties. Slightly more frequent in general US media discourse about political polls and medical studies.
Grammar
How to Use “confidence interval” in a Sentence
The confidence interval [is/was] [calculated] for X.We [report/present] a [95%] confidence interval [for/of] Y.The estimate, [with/bracketed by] its confidence interval, [suggests/shows] Z.Vocabulary
Collocations
Examples
Examples of “confidence interval” in a Sentence
noun
British English
- The 95% confidence interval for the unemployment rate was reported alongside the quarterly figures.
- Researchers always check if the confidence interval includes the null value, like zero.
American English
- The study's key finding was the confidence interval for the risk ratio, which did not cross 1.0.
- A narrow confidence interval indicates a more precise estimate from the survey data.
Usage
Meaning in Context
Business
"The forecast for Q3 revenue is £2.5M, with a 90% confidence interval of £2.2M to £2.8M, indicating moderate market volatility."
Academic
"The treatment effect was significant, with a mean difference of 0.5 (95% CI: 0.3 to 0.7, p < 0.01)."
Everyday
"The poll says 58% support the policy, but the confidence interval means the true support could be anywhere between 55% and 61%."
Technical
"A bootstrap method was used to derive bias-corrected and accelerated confidence intervals for the median."
Vocabulary
Synonyms of “confidence interval”
Strong
Neutral
Weak
Vocabulary
Antonyms of “confidence interval”
Watch out
Common Mistakes When Using “confidence interval”
- Saying 'There is a 95% probability the true mean is in this specific interval.' (Incorrect) vs. '95% of intervals calculated this way will contain the true mean.' (Correct frequentist interpretation).
- Confusing confidence interval with prediction interval or credible interval (Bayesian).
- Using 'confidence interval' to describe ranges in non-statistical contexts (e.g., 'my confidence interval for arrival is 3-4 PM').
FAQ
Frequently Asked Questions
Wider. To be more confident that you've captured the true parameter, you need a wider net (interval).
Yes, informally. If a 95% confidence interval does not include the null hypothesis value (e.g., 0 for a difference, 1 for a ratio), you can reject the null hypothesis at the 5% significance level.
The standard deviation measures the spread or variability of the raw data. A confidence interval measures the precision (or uncertainty) of an estimated statistic (like a mean) calculated from that data.
In strict frequentist statistics, the confidence level is a property of the *method*, not the *specific interval*. The interval either contains the true mean or it does not (probability is 0 or 1, not 0.95). The correct interpretation is about the long-run performance of the estimation procedure.
A range of values, derived from a sample, that is likely to contain the true value of an unknown population parameter with a specified level of probability (confidence level).
Confidence interval is usually formal, academic, technical (statistics, research, science, medicine) in register.
Confidence interval: in British English it is pronounced /ˈkɒn.fɪ.dəns ˌɪn.tə.vəl/, and in American English it is pronounced /ˈkɑːn.fə.dəns ˌɪn.t̬ɚ.vəl/. Tap the audio buttons above to hear it.
Phrases
Idioms & Phrases
- “To fall within the confidence interval”
- “The confidence interval brackets the true value”
- “Outside the confidence interval”
Learning
Memory Aids
Mnemonic
CONfidence INTERVAL = CONtains the true value with INTERVAL of doubt. Think of a net (the interval) that you are CONFIDENT will catch the fish (the true parameter).
Conceptual Metaphor
UNCERTAINTY AS A SPATIAL RANGE / KNOWLEDGE AS A CONTAINER. The 'true value' is contained within a 'box' (the interval) whose size reflects our confidence. More data builds a smaller, more precise box.
Practice
Quiz
What does a 95% confidence interval primarily tell us?