Confidence Interval Lower Limit Calculator

Confidence interval lower limit calculator is an essential tool for statistical analysis. It helps determine the lower bound of a confidence interval, providing a range within which the true population parameter is likely to fall.

1. Enter the sample size.
2. Select the desired confidence level.
3. Enter the margin of error.
4. Click ‘Calculate’.

The formula for calculating the confidence interval lower limit is:

Lower Limit = Sample Mean - (Z * Margin of Error)

Where Z is the Z-score corresponding to the chosen confidence level.

Z-Scores for Common Confidence Levels

Confidence Level	Z-Score
90%	1.645
95%	1.96
99%	2.576

• Always use a confidence level appropriate for your analysis.
• Ensure your sample size is large enough for accurate results.
• Consider using a different statistical method if your data is not normally distributed.

What is a confidence interval?

A confidence interval is a range of values around a sample statistic (like the mean) within which we are confident (to a certain degree) that the true population parameter lies.

BLS Handbook of Methods and UK Office for National Statistics provide more information on confidence intervals.