Confidence Interval Calculator
Calculate confidence intervals for statistical data with our simple and accurate confidence interval calculator.
Category: Math
Confidence Interval Calculator
Calculate the confidence interval for a sample mean
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About Confidence Intervals
Frequently Asked Questions
What is a confidence interval?
A confidence interval is a range of values that is likely to contain an unknown population parameter. For example, a 95% confidence interval for a population mean indicates that if you were to take many random samples from the population and calculate a 95% confidence interval for each sample, 95% of these intervals would contain the true population mean.
How do you interpret a 95% confidence interval?
A 95% confidence interval means that if you were to repeat your experiment many times, 95% of the calculated intervals would contain the true population parameter. It doesn't mean there's a 95% probability that the true parameter is within your specific interval.
What factors affect the width of a confidence interval?
Three main factors affect the width of a confidence interval: (1) Sample size: larger samples produce narrower intervals; (2) Confidence level: higher confidence levels (e.g., 99% vs 95%) produce wider intervals; (3) Standard deviation: greater variability in the data produces wider intervals.
When should I use a confidence interval?
Confidence intervals are useful whenever you want to estimate a population parameter from a sample. They are commonly used in market research, scientific studies, polls, surveys, and quality control to express the reliability of an estimate.