Monday, October 23, 2006

Productivity and Screen Size

Productivity from using large monitors ...

"A study of the benefits of big monitors fails on two accounts: it didn't test realistic tasks, and it didn't test realistic use. Productivity is a key argument for workplace usability, but you must measure it carefully.

In my column on how to design websites for ever-bigger screens, I mentioned that Apple had published a study of the productivity impact of big monitors. I didn't believe in Apple's methodology, so I didn't discuss the study further, but -- since it has now gotten significant press coverage -- I'll remedy this deficiency.

A prominent article about Apple's study reports, for example, that "cutting and pasting cells from Excel spreadsheets resulted in a 51.31% productivity gain -- a task that took 20.7 seconds on the larger monitor versus 42.6 seconds on the smaller screen."

First, let me note that reducing task time from 42.6 seconds to 20.7 seconds is actually a productivity gain of 105%, not 51%. Productivity is measured by how much value a worker produces per hour. With a small-screen task-time of 42.6 seconds, users can cut-paste 85 times in an hour, whereas with a large-screen task time of 20.7 seconds, they can cut-paste 174 times in an hour. In other words, the user's output increases from 85 to 174, meaning that big-screen users paste 105% more cells into their spreadsheet for each hour worked.

(As an analogy, assume that General Motors improved a factory so that 174 cars -- rather than their standard 82 -- rolled off assembly lines every hour. In that case, we'd say that productivity had improved by 105%, because the company would be getting more than twice as much output from the same number of workers.)

However, it doesn't matter what the exact number is, because it's irrelevant. Measurement studies are tricky to get right, and this study was wrong in so many ways that its numbers are meaningless."    (Continued via Alertbox)    [Usability Resources]


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