My computer uses commas as the decimal separator. When I paste numbers into InStat, it thinks the commas separate columns so pastes the decimal part into a separate column.

This is a problem with InStat 3.0b for Mac.

It is easy to work around. The trick is not to copy a single column, but rather copy two or more columns at a time (even if one is blank). When you paste two or more columns at once, InStat correctly deals with  commas as decimals (if that is how your Mac international control panel is set).