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Chapter 3 Engineering Design 47
size, shape, appearance, performance, diffi culty
to produce, ergonomics (ease of use), market-
ability, functionality, safety and liability, ethical
considerations, and other criteria specifi c to the
problem.
Each design must be evaluated based on the
criteria for the design listed previously. There are
many methods and techniques for evaluating
ideas against criteria. One way is to rank all crite-
ria in order of its importance. A numeric value is
then given to each of the criteria. Each idea can
then be given a numeric score based on how well
it meets the given criteria. It is imperative that
numeric values are scores that are assigned in an
objective way so the decision is based on facts
rather than simply selecting someone’s favorite
idea. All other factors being equal, the idea with
the highest numeric score is the best solution
given the criteria, Figure 3-8.
See Workbook Activity 3-4 to evaluate ideas
and determine the best solution to the design
problem.
The fi nal step in the solution creation step
is to communicate the solution. Rough sketches
were made in the ideation step to record ideas.
Now it is time to create full-color renderings,
detail drawings, and three-dimensional (3-D)
models so other people can understand the
chosen solution.
Research is another good way to develop
alternate solutions. Engineers do research in
libraries, on the Internet, through the United
States Patent and Trademark Offi ce, and in
other areas. Engineers speak with experts in the
fi eld and others with fi rsthand knowledge of
the problem at hand. Engineers often purchase
products that are already on the market to see
how they work and to see how they can be
improved.
See Workbook Activity 3-3 to use research
to generate ideas about a design problem.
Solution Creation
The goal of the solution creation step is to
sort through all the ideas from the idea gener-
ation stage and decide on the best possible
solution. This is the stage where each idea is
evaluated and tested to see if any will truly
solve the given problem. If more than one solu-
tion solves the problem, the best solution must
be selected and refi ned.
There are many ways to begin evaluat-
ing proposed solutions from the idea genera-
tion step. One way is to throw out all ideas that
do not truly solve the problem. Once the list is
narrowed down to ideas that could work, the
process of fi nding the best solution can begin.
The process of evaluating ideas is called design
analysis. Each idea is evaluated based on its cost,
Design Evaluation
Criteria Design #1 Design #2 Design #3
Appearance 7 3 6
Cost 2 8 3
Function 6 4 9
Production 5 7 8
Safety 6 5 7
Design Score 26 27 33
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Figure 3-8. 
Design evaluations are used to rate and select designs.