Title: Understanding Confidence Intervals | Easy Examples & Formulas
Headings: Confidence intervals explained
Confidence intervals explained
What exactly is a confidence interval?
Confidence level = 1 − a
When do you use confidence intervals?
Calculating a confidence interval: what you need to know
Point estimate
Finding the critical value
Finding the standard deviation
Sample size
What can proofreading do for your paper?
Confidence interval for the mean of normally-distributed data
Confidence interval for proportions
Confidence interval for non-normally distributed data
Reporting confidence intervals
Caution when using confidence intervals
Frequently asked questions about confidence intervals
What is the difference between a confidence interval and a confidence level?
How do you calculate a confidence interval?
What is a standard normal distribution?
What are z-scores and t-scores?
What is a critical value?
What does it mean if my confidence interval includes zero?
How do I calculate a confidence interval if my data are not normally distributed?
Is this article helpful?
Rebecca Bevans

Content: What exactly is a confidence interval? A confidence interval is the mean of your estimate plus and minus the variation in that estimate. This is the range of values you expect your estimate to fall between if you redo your test, within a certain level of confidence. Confidence, in statistics, is another way to describe probability. For example, if you construct a confidence interval with a 95% confidence level, you are confident that 95 out of 100 times the estimate will fall between the upper and lower values specified by the confidence interval. Your desired confidence level is usually one minus the alpha ( a ) value you used in your statistical test: Confidence level = 1 − a
So if you use an alpha value of p < 0.05 for statistical significance, then your confidence level would be 1 − 0.05 = 0.95, or 95%. When do you use confidence intervals? You can calculate confidence intervals for many kinds of statistical estimates, including: Proportions
Population means
Differences between population means or proportions
Estimates of variation among groups
These are all point estimates, and don’t give any information about the variation around the number.