6 Sigma is the application of statistics, "data-driven decision making", and sigma being the phrase used for a standard deviation, taking something to six standard deviations is about as close to perfection as is reasonably possible (1.37 defects per million opportunities I recall) - it's something that I did in a previous life at Caterpillar (making diggers, not boots...) Anovas and T-tests were some of the analyses that we used to do on data that we'd gathered. I remember Anova meaning Analysis of Variants and it was useful to see whether a variable had a significant influence on the outcome of things...
