# Documentation/Calc Functions/CONFIDENCE

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CONFIDENCE

## Category:

Statistical Analysis

## Summary:

Returns the (1-alpha) confidence interval for a normal distribution.

## Syntax:

CONFIDENCE(Alpha; StDev; Size)

## Returns:

Returns a non-negative real number which is the confidence interval for a population mean with significance level as Alpha, standard deviation of population as StDev and size of population as Size,calculated using a normal distribution.

## Arguments:

Alpha is a real number in range 0 to 1 or a reference to the cell containing that number which is the level of the confidence interval.

StDev is a positive real number or a reference to the cell containing that number which is the standard deviation for the total population.

Size is an integer value greater than equal to 1 or a reference to the cell containing that number which is the size of the total population.

• If Alpha is less than equal to 0 or greater than equal to 1, then the function returns an error value.
• If StDev is less than or equal to 0, then the function returns an error value.
• If Size is not an integer than the function uses its floor value, i.e. it is truncated to an integer.
• If Size is less than 1, then the function returns an error value.

## Additional details:

For more details on the CONFIDENCE function, check the confidence level, and normal distribution by visiting Wikipedia and Wikipedia2.

## Examples:

Formula Description Returns
=CONFIDENCE(0.05;2.5;50) The function calculates the confidence interval for the mean of a population for a sample size of 50, with a 5% significance level and a standard deviation of 2.5 based on a normal distribution. 0.692951912174839
=CONFIDENCE(0.05;1.5;100) The function calculates the confidence interval for the mean of a population for a sample size of 100, with a 5% significance level and a standard deviation of 1.5 based on a normal distribution. 0.293994597681008

CONFIDENCE