Confidence Interval Metric
What is a Confidence Interval?
A Confidence Interval (CI) is a range of values that is likely to contain the true population parameter with a specified probability (confidence level).
Interpretation
- 95% CI: If we repeated the study 100 times, about 95 of the CIs would contain the true value
- Wider CI: More uncertainty in the estimate
- Narrower CI: More precision
Common Confidence Levels
- 90%: Less strict
- 95%: Most common
- 99%: More strict
Example
Mean height = 170 cm (95% CI: 165-175 cm)
- The true population mean is likely between 165 and 175 cm
Statistical Significance
- If 95% CI for difference includes 0: Not significant
- If 95% CI for difference excludes 0: Significant
Related Terms
- P-Value: Related significance measure
- Standard Error: Used to calculate CI