Ideally, measure directly, and assign a value to that measurement. Make sure that inverse relationship is accounted for. Destructive tests (may or may not be desirable) Make sure you are measuring as directly as possible. Repeatability (any rater should give same result) Unambiguous (everyone should come to same conclusion) Betsy had hard time peeling an apple. Betsy was very involved in prototyping and the process of developing a new object. Betsy"s husband sam who has a businessman/market executive saw a market opportunity and contracted a design firm giving them 3% of possible future profits. Betsy"s implied solution was a better handle to grip the peeler. Design a peeler that is suitable for people with arthritis. Objectives include: ergonomic, lightweight, easy to clean, versatile, compact, safe, reasonably priced, easy to hold. Constraints include: size, non-toxic (food safe), lightweight, cost, dishwasher safe, corrosion proof. Advantage of single handle design for multiple devices.