What is Efficiency?
A usability metric that measures how easily a task is completed with a given interface (eg, time to completion, number of keystrokes to completion). The metric is measurable in quantitative terms.
Efficiency is the ratio of useful work performed to the total resources expended. Design efficiency in as the quotient of dividing the material gain (M+) by resources used (R) within an activity. The efficiency of the design work can be viewed as the effectiveness of the result against the input made, while timing is an important aspect. The ability to produce effective designs with efficiency is important within design work, either at the school level or professionally. If we are skilled we can spend more time developing designs effectively and therefore get the most out of practice and improve the effectiveness of the result.