Statistical - CONFIDENCE.NORM Function

Description

The CONFIDENCE.NORM function returns the confidence interval for a population mean, using a normal distribution.

The confidence interval is a range of values. Your sample mean, x, is at the center of this range and the range is x ± CONFIDENCE.NORM.

CONFIDENCE.NORM (alpha,standard_dev,size)

Argument	Description	Required/ Optional
Alpha	The significance level used to compute the confidence level. The confidence level equals 100*(1-alpha)% In other words, an alpha of 0.05 indicates a 95 percent confidence level.	Required
Standard_dev	The population standard deviation for the data range and is assumed to be known.	Required
Size	The sample size.	Required

Argument

Description

Required/ Optional

Alpha

The significance level used to compute the confidence level.

The confidence level equals

100*(1-alpha)%

In other words, an alpha of 0.05 indicates a 95 percent confidence level.

Required

Standard_dev

The population standard deviation for the data range and is assumed to be known.

Required

Size

The sample size.

Required

If we assume alpha equals 0.05, we need to calculate the area under the standard normal curve that equals (1 - alpha), or 95 percent. This value is ± 1.96. The confidence interval is therefore −

$$\bar{x}\pm 1.96\left ( \frac{\sigma }{\sqrt{n}} \right )$$
If size is not an integer, it is truncated.
If size < 1, CONFIDENCE.NORM returns the #NUM! error value .
If alpha ≤ 0 or alpha ≥ 1, CONFIDENCE.NORM returns the #NUM! error value .
If standard_dev ≤ 0, CONFIDENCE.NORM returns the #NUM! error value.
If any argument is nonnumeric, CONFIDENCE.NORM returns the #VALUE! error value .

Excel 2010, Excel 2013, Excel 2016

advanced_excel_statistical_functions.htm