CONFIDENCE.NORM function - The function returns the confidence interval of the population by using a normalized distribution in Excel

The following article introduces you to CONFIDENCE.NORM - one of the functions in the group of statistical functions that is very popular in Excel.

Description: The function returns the confidence interval for the population by using normalized distributions. Support functions from Excel 2010 onwards.

Syntax: CONFIDENCE.NORM (alpha, standard_dev, size)

Inside:

- alpha: The critical level to calculate the confidence level, with confidence level = 100 * (1- alpha) , is the required parameter .

- standard_dev: The overall standard deviation for the data range, and considered to have been determined, is the required parameter.

- size: Sample size , is a required parameter.

Attention:

- If any of the parameters' values ​​are not numeric -> the function returns the #VALUE! Error value .

- If alpha ≤ 0 or alpha ≥ 1 -> the function returns the #NUM! Error value

- If standard_dev ≤ 0 -> the function returns the #NUM! Error value

- If size is not an integer -> it is truncated to an integer.

- If size ≤ 1 -> the function returns the #NUM! Error value

- If deg_freedom <1 or deg_freedom> 10 ^ 10 -> the function returns the #NUM! Error value

- Assuming alpha = 0.5 -> confidence interval is:

[overline chi pm 1.96left ({frac {sigma} {{sqrt n}}} right)]

For example:

Calculate the average overall confidence interval with the data in the table below:

- In the cell to calculate, enter the formula: = CONFIDENCE.NORM (D6, D7, D8)

- Press Enter -> the overall confidence interval for the population is:

- Where alpha ≤ 0 or alpha ≥ 1 -> the function returns the #NUM! Error value

- Where size ≤ 1 -> the function returns the #NUM! Error value

Above are instructions and some specific examples when using the CONFIDENCE.NORM function in Excel.

Good luck!