What is confidence? Part 2: Detailed definition and determination of confidence intervals

Ann Emerg Med. 1997 Sep;30(3):311-8. doi: 10.1016/s0196-0644(97)70167-7.

Abstract

In many cases, CIs should be reported in place of P values. The lower limit of a 95% CI is chosen such that the probability of obtaining the value observed in the trial or a greater value is .025 and the upper limit such that the probability of obtaining the value observed or a lesser value is also .025. CIs for data from most clinical trials may be calculated easily with the use of formulas given in this article. A 95% CI is not the same as a 95% probability interval. The 95% CI contains values statistically consistent with the data obtained, whereas a 95% probability interval has a 95% probability of containing the true value of interest.

MeSH terms

  • Confidence Intervals*
  • Data Interpretation, Statistical
  • Evaluation Studies as Topic
  • Odds Ratio