Confidence Interval Calculator
Introduction & Importance
Calculate the upper and lower limits of the confidence interval is a crucial statistical process…
How to Use This Calculator
- Enter your sample size.
- Select your desired confidence level.
- Input the mean and standard deviation of your data.
- Click ‘Calculate’.
Formula & Methodology
The formula for calculating the confidence interval is…
Real-World Examples
Example 1: A survey of 100 people found a mean satisfaction score of 8.5 with a standard deviation of 1.2…
Example 2: A study of 500 patients found a mean recovery time of 12.3 days with a standard deviation of 2.1…
Example 3: A poll of 200 voters found a mean approval rating of 54.7% with a standard deviation of 3.4…
Data & Statistics
| Sample Size | Confidence Level (90%) | Confidence Level (95%) | Confidence Level (99%) |
|---|---|---|---|
| 30 | 5.83 | 6.63 | 9.37 |
| 100 | 3.29 | 4.03 | 5.84 |
| 1000 | 1.00 | 1.28 | 1.96 |
| Standard Deviation | Confidence Level (90%) | Confidence Level (95%) | Confidence Level (99%) |
|---|---|---|---|
| 1 | 2.58 | 3.00 | 4.26 |
| 2 | 5.16 | 6.00 | 8.53 |
| 3 | 7.71 | 8.66 | 12.71 |
Expert Tips
- Always ensure your sample size is large enough to provide accurate results.
- Be aware of the assumptions behind the confidence interval calculation.
- Consider using a t-distribution instead of a z-score for smaller sample sizes.
Interactive FAQ
What is a confidence interval?
A confidence interval is a range of values around a sample statistic (like the mean) that indicates the reliability of an estimate…
Why is it important to calculate confidence intervals?
Calculating confidence intervals helps us understand the reliability of our estimates and makes it easier to compare different studies…
For more information, see the U.S. Census Bureau’s guide to confidence intervals and the Statistics How To’s explanation of confidence intervals.