Invented by Genrikh Altshuller, TRIZ analyzes engineering problems and then suggests solutions based on structure. Inventive problems contain at least one contradiction which arise when improving one feature detracts from another.
Design for Excellence (aka Design for X, DFX) is a systematic approach for designing where X is the objective for the product or process
FMEA (Failure Mode Effects Analysis) is a tool that helps us anticipate what might go wrong with a process and identify the possible causes.
Taguchi Robust Design is a function of product design. Robust products have a strong signal-to-noise ratio.
The 5 Whys is a root cause analysis technique used in the Analyze phase of the Six Sigma DMAIC (Define, Measure, Analyze, Improve, Control).