A to Z of Excel Functions: the CONFIDENCE.T Function
11 October 2017
Welcome back to our regular A to Z of Excel Functions blog. Today we look at the CONFIDENCE.T function.
The CONFIDENCE.T function
Have you got your CONFIDENCE down to a T? This function first appeared in Excel 2010 but unlike CONFIDENCE.NORM there was no equivalent in earlier versions of Excel. That is because this function returns the confidence interval for a population mean, using a Student’s t distribution.
The CONFIDENCE.T function employs the following syntax to operate:
CONFIDENCE.T(alpha, standard_dev, size)
- alpha: this is required. This represents 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: this is also required. This is the population standard deviation for the data range and is assumed to be known
- size: also required. This is the sample size.
It should be further noted that:
- if any argument is non-numeric, CONFIDENCE.T returns the #VALUE! error value
- if alpha is ≤ 0 or ≥ 1, CONFIDENCE.T returns the #NUM! error value
- if standard_dev ≤ 0, CONFIDENCE.T returns the #NUM! error value
- if size is not an integer, it is truncated
- if size < 1, CONFIDENCE.T returns the #DIV/0! error value
Please see my example below:
We’ll continue our A to Z of Excel Functions soon. Keep checking back – there’s a new blog post every other business day.