In statistics, a confidence interval (CI) is a type of estimate computed from the statistics of the observed data. This proposes a range of plausible values for an unknown parameter (for example, the mean). The interval has an associated confidence level that the true parameter is in the proposed range. Given observations , …, and a confidence level , a valid confidence interval has a. If you know the standard deviation for a population, then you can calculate a confidence interval (CI) for the mean, or average, of that population. When a statistical characteristic that’s being measured (such as income, IQ, price, height, quantity, or weight) is numerical, most people want to estimate the mean (average) value for the population. … You can find the confidence interval (CI) for a population proportion to show the statistical probability that a characteristic is likely to occur within the population. When a characteristic being measured is categorical — for example, opinion on an issue (support, oppose, or are neutral), gender, political party, or type of behavior (do/don’t wear a … When you don’t know anything about a population’s behavior (i.e. you’re just looking at data for a sample), you need to use the t-distribution to find the confidence interval.That’s the vast majority of cases: you usually don’t know population parameters, otherwise you wouldn’t be looking at statistics!. The confidence interval tells you how confident you are in your results. What is a Confidence Interval? Confidence intervals are an essential part of inferential statistics, upon which most market research is based. Put simply, in statistics, a confidence interval is a type of interval estimate that is computed from the data that has been observed from a sample. This feature is not available right now. Please try again later. When you calculate a confidence interval, you use the result to present your mean value alongside your level of uncertainty. For example, you might have a mean of 130 pounds and write 130 ± 12 pounds, indicating that the true mean value is somewhere between 118 and 142, or 130 pounds (CI: 118 to 142 pounds), where the CI stands for confidence interval. How to Calculate Confidence Interval. A confidence interval is an indicator of your measurement's precision. It is also an indicator of how stable your estimate is, which is the measure of how close your measurement will be to the original. Confidence Intervals. An interval of 4 plus or minus 2. A Confidence Interval is a range of values we are fairly sure our true value lies in.