Very cheap software (you pay for a three year licence) and very easy to use, as it is based on a spreadsheet. Indeed, it is possible to copy and paste data between Excel and StatsDirect. Also, for those who are not well-versed in statistics, there is an inexpensive book by Cole Davis called Statistical Testing in Practice, which teaches basic statistics (and some more complex stuff as well), using StatsDirect:

Pages in category "StatsDirect"

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