Confidence Interval Calculator (1 or 2 means)

Calculate the confidence interval of a sample set. Enter the sample number, the sample mean, and standard deviation to calculate the confidence interval.

Click Here or Scroll Down for Two Means Calculator

Confidence Interval Formula

The confidence of a sample set can be calculated through the following formula:

X  ±  Zs√(n)

  • Where X is the mean
  • Z is the Z-Value
  • s is the standard deviation
  • n is the number of sample

The z-value or z-score can be calculated using the table below.

Confidence LevelZ
80%1.282
85%1.44
90%1.645
95%1.96
99%2.576
99.50%2.807
99.90%3.291

How to calculate a confidence interval?

Time needed: 10 minutes.

How to calculate a confidence interval?

  1. First, you need to calculate the mean of your sample set.

    This can be done by summing the entire set of numbers and then dividing by the total numbers in the sample set. Another word for the mean is average.

  2. Next, you need to determine the z-score.

    This is done through the use of the table above. Simply select the confidence level you wish to calculate the confidence interval at, and use the table to grab the z-value.

  3. Calculate the standard deviation

    Standard Deviation Formula

  4. Finally, enter the values into the calculator.

    Alternatively, you could simply enter the values into the formula and calculate using a normal calculator.

FAQ

What is a confidence interval?

A confidence interval is a type of estimate in statistics that shows a possible range of values for an unknown variable or parameter.

How do i choose a confidence level?

A confidence level is going to be chosen based on the statistics and outcomes being analyzed. If you have greater confidence in your data, chose a higher confidence level.

Why is the solution two different values?

A confidence interval is a range of values based around the mean. As a result, the solution will be both the upper and lower bounds of that range of values.

Confidence Interval of Two Means Calculator

This calculator determines the confidence interval of two means, and their corresponding data. You will enter the same information for each data set, just as you would in the normal calculator above.

For more related calculators, click here.

confidence interval calculator
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