# Documentation/Calc Functions/CONFIDENCE

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.

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