There are many different error messages that you might see if your formulas are incorrectly written.
Building better formulas in Excel usually boils down to increasing your knowledge of using functions and avoiding some of the common mistakes that many people make.
The main thing is to use the right function and to know how to write a proper formula. Using an incorrectly written formula—or the wrong function—usually results in an incorrect answer.
These problems are encountered by anyone using Excel, not just those using statistical functions. For the basics on writing formulas in Excel, see the course Find functions and enter arguments.