# CONFIDENCE

CONFIDENCE(alpha, standard_dev, size)

Returns the confidence interval for a population mean.

 alpha The significance level used. standard_dev The population standard deviation for the data range. size The size of the sample.

 REMARKS
 * CONFIDENCE.NORM was added in Excel 2010 to replace this function.* The confidence level equals 100*(1 - alpha)%.* An alpha of 0.05 indicates a 95 percent confidence level.* An alpha of 0.1 indicates a 90 percent confidence level.* If any of the arguments are not numeric, then #VALUE! is returned.* If "alpha" = 0, then #NUM! is returned.* If "alpha" = 1, then #NUM! is returned.* If "standard_dev" = 0, then #NUM! is returned.* If "size" is not an integer, it is truncated.* If "size" < 1, then #NUM! is returned.* For the Microsoft documentation refer to support.microsoft.com

 A 1 =CONFIDENCE(0.05,2.5,50) = 0.693 2 =CONFIDENCE(0.05,2.5,50.25) = 0.693 3 =CONFIDENCE(-1,2.5,50) = #NUM! 4 =CONFIDENCE(0.05,0,50) = #NUM! 5 =CONFIDENCE(1,2.5,50) = #NUM! 6 =CONFIDENCE("some text",2.5,50) = #VALUE!