• Theories should be more central to research and practice. A good theory should
guide researchers in understanding relationships between concepts and generalizing
results. It should also guide practitioners when making design
tradeoffs for products. The power of theories to shape design is most apparent
in focused theories such as COMS or Fitts's Law; it is more difficult to
demonstrate for explanatory theories, whose main impact may be in educating
the next generation of designers or guiding research.
• Theories should lead rather than lag behind practice. Critics remark that too often a
theory is used to explain what has been produced by commercial product
designers. A robust theory should predict or at least guide practitioners in
designing new products. Effective theories should suggest novel products
and help refine existing ones.