What are the differences between common statistical tests?

Statistics are essential components of quantitative (and qualitative) research that we all should know. We have sat through numerous lectures on the subject, and we know that we need to understand it and really should by now, even if only to not appear un-knowledgeable at journal club meetings. Still many people skip the section on statistical analysis when reading papers. Sometimes it feels that only those who have performed full time research really understand statistics - and not even then if they were lucky enough to have a statistician on their team. As part of our series of research tutorials we would now like to remove some of the mystery surrounding the art of statistics. Let’s start with the raw data….