"Persons who desire to use a spreadsheet package to perform statistical analyses are advised to use Gnumeric rather than Excel." says a report. Here is the report:
The open source spreadsheet package "Gnumeric" was such a good clone of Microsoft Excel that it even had errors in its statistical functions similar to those in Excel's statistical functions. When apprised of the errors in v1.0.4, the developers of Gnumeric indicated that they would try to fix the errors. Indeed, Gnumeric v1.1.2, has largely fixed its flaws, while Microsoft has not fixed its errors through many successive versions. Persons who desire to use a spreadsheet package to perform statistical analyses are advised to use Gnumeric rather than Excel.
See: http://www.csdassn.org/reportdetail.cfm?ID=508