The ease with which you can perform multiple types of analyses - including correlations or regressions! I dislike not being able to run more advanced tests like t-tests in certain circumstances (such as when using mixed models).I also find it hard to understand how results are interpreted without first familiarizing myself with their explanations! This is very important so that mistakes don't get made during my analyses.Statistilx makes analyzing research studies easier than other software alternatives out there.The ability to do several different types of statistics/analyses at one time has proven quite useful.It works well for all types of complex analyses, so if you're interested take advantage of this free software that's available for everyone :) Very easy website navigation system, quick download times, intuitive interface and user friendly explanations regarding what each button does is wonderful. There are even plenty of training videos to watch before starting your own projects, if needed! The tool works well with our existing databases - not sure about any specific features but we are able create custom reports using SQL queries within Statistixl. I can't think of anything negative at this time. We have been working for over 5 years now without issues or other problems. This software has allowed us to provide better reporting capabilities than ever before!