Forum Discussion
What is the difference between the functions correl and pearson?
To my knowledge they have exactly the same math behind, but different implementation. On Excel after 2003 it shall be no difference. Bit more is within this article https://docs.microsoft.com/en-us/office/troubleshoot/excel/statistical-functions-rsq
Again, I don't know. At least CORREL() is not marked "This function is available for compatibility..." as some others if you start typing them.
Performance - I did small simple test with two arrays on 1 million rows each. Bot CORREL() and PEARSON() calculates practically immediately.
You would need to run that test in a version of Excel prior to Excel 2003, because that is when pearson() would sometimes yield erroneous results. It would have made sense to use pearson() back then if it ran a lot faster than correl() and if you knew how to determine that you were not using it in a domain that would yield errors.
Perhaps, but performance and errors in some situations are different things.
I just took another look at that article you linked to, and it's interesting that the issue is explained (somewhat) in a troubleshooting article about function rsq(), which is just the square of pearson(), and is not explained in the function documentation articles about correl(), pearson(), or rsq().