Stata is statistical software from StataCorp that is commonly used by economists, political scientists, and others in academia. Stata is considered to be more powerful than SPSS with excellent syntax and programming capabilities, though not necessarily as flexible as SAS and R. People who know Stata often prefer it over SPSS and SAS because of the balance between difficulty and power. However, it is used far less than the other statistical softwares.
NYU's Quantitative Analysis Guide - Look-up table to choose a statistical test
Links directly to relevant pages in the following useful resources
Examples with syntax