# Documentation/Calc Functions/CONFIDENCE.T

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## Function name:

CONFIDENCE.T

## Category:

Statistical Analysis

## Summary:

Returns the (1-alpha) confidence interval for a Student's t-distribution.

## Syntax:

CONFIDENCE.T(**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 Student's t 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 or equal to 1, then the function returns an error value.

## Additional details:

For more details on the CONFIDENCE.T function, check the confidence level, and Student's t-distribution by visiting [https://en.wikipedia.org/wiki/Confidence_interval Wikipedia] and Wikipedia2.

## Examples:

Formula | Description | Returns |
---|---|---|

=CONFIDENCE.T(0.05,1,50) | The function calculates confidence interval for the mean of a population for a sample size of 50, with a 5% significance level and a standard deviation of 1 based on a Student's t-distribution. | 0.28419685549573 |

=CONFIDENCE.T(0.05;1.5;100) | The function calculates 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 Student's t-distribution. | 0.297632542737962 |

## Related LibreOffice functions:

## ODF standard:

None

## Equivalent Excel functions:

CONFIDENCE.T