A cause and effect matrix is a six sigma tool that prioritizes the key process input variables based on priorities of customer outputs.
FMEA (Failure Mode Effects Analysis) is a tool that helps us anticipate what might go wrong with a process and identify the possible causes.
A Cause and Effect Diagram (aka Ishikawa, Fishbone) showing possible causes (process inputs) for a given effect (process outputs).
A Paired T Distribution, Paired T-Test, Paired Comparison test, and Paired Sample Test compares the mean & standard deviation of two groups.
One Sample T Hypothesis Test (Student’s T Test) are used to resolve hypothesis tests around comparing process means ( sample size to be <30)