Interpret a 95% confidence interval in a health study.

• A. We are 95% confident the true parameter lies within the interval; a narrower interval indicates greater precision; if the interval for a relative measure does not include the null, the result is statistically significant.
• B. There is a 95% probability that the parameter lies in the interval after data collection.
• C. The interval guarantees significance regardless of the null value.
• D. CI is the same as a p-value.

Answer: (A)