| Spread WinRT Documentation > Formula Reference > Formula Functions > CONFIDENCE | 
This function returns confidence interval for a population mean.
CONFIDENCE(alpha,stdev,size)
This function has these arguments:
| Argument | Description | 
|---|---|
| alpha | Alpha, significance level used in calculating confidence level, where confidence level is 100 times (1-alpha)% | 
| stdev | Population standard deviation for the range | 
| size | Number representing the size of the sample; if not an integer, the number is truncated | 
Accepts numeric data for all arguments. Returns numeric data.
CONFIDENCE(0.5,B4,D5)
CONFIDENCE(0.5,R4C2,R5C4)
CONFIDENCE(0.05,3.5,150) gives the result 0.560106363