CONFIDENCE.NORM function: Description, Usage, Syntax, Examples and Explanation

Syntax of CONFIDENCE.NORM function

CONFIDENCE.NORM(alpha,standard_dev,size)

The CONFIDENCE.NORM function syntax has the following arguments:

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

CONFIDENCE.NORM formula explanation

• If any argument is nonnumeric, CONFIDENCE.NORM returns the #VALUE! 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 size is not an integer, it is truncated.
• If size < 1, CONFIDENCE.NORM returns the #NUM! error value.
• 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:

Example of CONFIDENCE.NORM function

Steps to follow:

1. Open a new Excel worksheet.

2. Copy data in the following table below and paste it in cell A1

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You can adjust the column widths to see all the data, if need be.