In judging the efficiency of a system, look beyond just the efficiency of the machine. People cost a lot more money than machines, and while it might appear that increasing machine productivity must result in increasing human productivity, the opposite is often true. As a single example, forcing customers to enter telephone numbers without normal spacing or punctuation saves a single line of code and a handful of machine cycles. It also results in a lot of incorrectly captured phone numbers as people cannot scan clusters of ten or more digits to discover errors. (That’s exactly why phone numbers are broken up into smaller pieces.) The amount of time wasted by just one person in your company trying to track down the correct version of an incorrectly entered phone number would sweep away the few minutes it would have taken to code the entry form so users could scan and correct their errors. Wrong numbers also can and do result in a lost sales. How many trillions of machine cycles would the profit from a single lost sale have covered?
Typically, the highest expense by far in a business is labor cost. Any time an employee must wait for the system to respond before they can proceed, money is being lost.
Large organizations tend to be compartmentalized, with each group looking out for its own interests, sometimes to the detriment of the organization as a whole. Information technology departments often fall into the trap of creating or adopting systems that result in increased efficiency and lowered costs for the information resources department, but at the cost of lowered productivity for the company as a whole. It is your job to run the studies that prove out whether new designs based on new, money-saving technologies will increase or decrease overall productivity among the affected workers and, if so, by how much and with what result to the corporation’s bottom line.
Work with HR or department heads to find out the average cost per hour of affected employees. (An honored rule of thumb is to take their hourly wage and multiply it by three to include all the other overhead associated with an employee, from rent to heat, lights, computer support, etc.) Multiply the overhead cost x the number of affected employees x the time an activity takes x the difference in productivity, positive or negative, in carrying out the activity to find the actual cost of a change. A positive number will help you sell your group and your design. A negative number will help your company from making a costly mistake.
This simple truth is why it is so important for everyone involved in a software project to appreciate the importance of making user productivity goal number one and to understand the vital difference between building an efficient system and empowering an efficient user. This truth is also key to the need for close and constant cooperation, communication, and conspiracy between engineers and human interface designers if this goal is to be achieved.
Look at the difference between the iPad and the netbook computers it crushed. The differences had nothing to do with what key you pressed to open an email. They had to do with things like not having to press any key at all.
Error messages must be written by a skilled writer to:
1. Explain what’s wrong
2. Tell the user specifically what to do about it
3. Leave open the possibility the message is improperly being generated by a deeper system malfunction
“Error -1264” doesn’t do any of these. Rare is the error message that covers even Point One well. Yours should cover all three. Your Quality Assurance group should be charged with the responsibility for reporting back to you any message that does not fulfill the criteria.
Many other principles in this list affect Efficiency, Latency Reduction and Readability in particular.