ECE194 S’01 Introduction to Engineering Design Arizona State University 1 The Statement-Restatement Technique “Engineering is an iterative process; one should be prepared to reconsider assumptions, decisions, and conclusions reached during the earlier stages of the design process if any new results indicate the need to do so.” Selected comments from Voland, Chapter 3

ECE194 S’01 Introduction to Engineering Design Arizona State University 2 The Statement-Restatement Technique “The initial problem statement may be too vague, ill-conceived, or simply incorrect.” “An incorrect problem statement is very unlikely to lead to the optimal solution of a problem.”

ECE194 S’01 Introduction to Engineering Design Arizona State University 3 The Statement-Restatement Technique One approach for properly formulating a problem is the Statement-Restatement technique. The underlying principle of this technique is that by restating the problem in different forms, one will develop a deeper and more accurate under- standing of the actual problem that needs to be solved. This technique has four objectives: 1. Determine the real problem 2. Determine actual constraints or boundaries 3. Identify meaningful goals 4. Identify relationships between inputs, outputs, and any unknowns

ECE194 S’01 Introduction to Engineering Design Arizona State University 4 The Statement-Restatement Technique The process is the following: Vary the emphasis on certain words and phrases Substitute explicit definitions for key words Change positive terms to negatives and vice versa Replace persuasive and/or implied words and investigate the underlying reasoning; express words in graphical or mathematical forms

ECE194 S’01 Introduction to Engineering Design Arizona State University 5 The Statement-Restatement Technique Original problem statement: Cereal is not getting to market fast enough to maintain freshness Varying the emphasis on certain words and phrases Cereal is not getting to market fast enough to maintain freshness (Do we haveother products that get there faster?) Cereal is not getting to market fast enough to maintain freshness (Can we make the distance/time shorter?) Cereal is not getting to market fast enough to maintain freshness (Can we distribute from a centalized location?) Cereal is not getting to market fast enough to maintain freshness (How can we keep cerreal fresher, longer?)

ECE194 S’01 Introduction to Engineering Design Arizona State University 6 The Statement-Restatement Technique Substitute explicit definitions for key words Breakfast food that comes in a box is not getting to the place where it is sold fast enough to keep it from getting stale (Makes us think about the package and the problem of staleness

ECE194 S’01 Introduction to Engineering Design Arizona State University 7 The Statement-Restatement Technique Change positive terms to negatives and vice versa Cereal is not getting to market fast enough to maintain freshness How can we find a way to get the cereal to market so slowly that it will never be fresh? (Makes us think about how long we have to maintain freshness and what controls it)

ECE194 S’01 Introduction to Engineering Design Arizona State University 8 The Statement-Restatement Technique Replace persuasive and/or implied words and investigate the underlying reasoning; express words in graphical or mathematical forms Problem statement implies that slow delivery causes the problem. Maybe the store holds it too long. Maybe it’s stale before it gets to the store. freshness = k time since baking What is k? How can it be increased?

ECE194 S’01 Introduction to Engineering Design Arizona State University 9 The Statement-Restatement Technique Instructions were given by the manager of an aspirin company to his employees: Find a way to put a pleasant-tasting coating on the aspirin tablets. (Attempts at spraying a coating were unsuccessful as the coating was very non-uniform)