Confidence Interval Calculator Lower And Upper Bound

Confidence intervals are crucial in statistics as they provide a range of values within which we can be confident that the true population parameter lies. The lower and upper bounds of this interval give us a sense of the uncertainty around our estimate.

1. Enter your sample size.
2. Select your desired confidence level.
3. Enter the standard deviation of your data.
4. Click ‘Calculate’.

The formula for calculating the confidence interval is:

Confidence Interval = Sample Mean ± (Z * (Standard Deviation / √Sample Size))

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

Comparison of Confidence Intervals at Different Levels

Confidence Level	Z-score	Margin of Error
90%	1.645	0.082
95%	1.96	0.1
99%	2.576	0.128

• Always use the appropriate Z-score for your desired confidence level.
• Consider the sample size and standard deviation when interpreting the results.
• Remember that the confidence interval is not a prediction interval.

What is the difference between a confidence interval and a margin of error?

The margin of error is the half-width of the confidence interval. The confidence interval is the range of values within which we are confident that the true population parameter lies.

For more information, see the confidence interval formula guide from Statistics How To.