SGNU PSPP is a program for statistical analysis of sampled data. It is a Free replacement for the proprietary program SPSS, and appears very similar to it with a few exceptions.
If your research requires some heavy-duty statistical analysis in order to interpret your results, this may require you to devote a significant section of your dissertation to presenting the results. This software is free to download and use to help you subject your data to startistical analysis. It might take some time to familiarise yourself with its operation, so you will need to evaluate if the benefits outweight the effort. As always, only use statistics that you understand and can explain clearly.