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"  Every time I download or install a file, I get a progress bar that gives me no indication of how long the process will take. Why can&amp;#039;t anyone make these things accurate? A progress bar is never a good sign. It means that your computer is held up and that you&amp;#039;re in for a wait. The frustration of waiting for a process to complete itself is compounded by another unfortunate fact: The progress bar is essentially lying to you. More often than not, your computer has no idea how long the process will takehitting the 50 percent mark might mean you&amp;#039;re halfway done, or it could just as well mean that you&amp;#039;ve barely gotten started.   Probably the most common progress indicator is the file download bar found in Web browsers. Download time should be easy to predict: All a computer needs to do is divide the total file size by the measure rate of download. But download speed is unpredictable, subject to the ebbs and flows of your connection, the busyness of the file&amp;#039;s server, and the performance of your router.   The progress bar for an application installer, or setup file, is an order of magnitude more complicated than a download-progress bar. It must track hundreds of different operations, each of which is dependent on external factors such as computer speed, Internet connectivity, and user activity. Brad Myers, a professor at Carnegie Mellon&amp;#039;s Human-Computer Interaction Institute, puts it thus: &amp;quot;There are many areas of computing where the system as a whole cannot predict how long [a task] will take, so progress bars don&amp;#039;t move in a consistent way.&amp;quot; Estimating how long it will take to install something as complex as a computer game borders on guesswork.   The result? App developers don&amp;#039;t always bother to make their progress bars accurate. Instead, they use freely available off-the-shelf progress-bar code that tracks how many raw operations have been completed, granting no special weight to those that may take longer than others. In some situations, developers give up entirely on traditional, determinate progress bars, resorting to indeterminate progress bars, or throbbers, in user-interface parlance. These indicators look and move in ways that suggest progressthink spinning pinwheelsbut really just repeat until the task is complete.   Chris Harrison, a Ph.D. candidate at Carnegie Mellon, is attacking the problem of the progress bar from an unusual angle. Using principles from the nascent field of psychology called time design, he has figured out a way to make a progress bar feel like it&amp;#039;s moving faster than it actually is. After testing different movement patternslinear, surging, fast-then-slowalong with different animations, Harrison arrived at the fastest-feeling, albeit fundamentally dishonest, progress bar: one that speeds up as it progresses, and contains a backward-moving ripple animation.   Alas, the progress bar is a necessary evil. &amp;quot;Unfortunately, there will always be computer programs that cannot be executed instantaneously,&amp;quot; wrote Myers in his bizarrely engrossing 1985 paper, &amp;quot;The Importance of Percent-Done Progress Indicators for Computer-Human Interfaces.&amp;quot; Today, that statement holds true: &amp;quot;As long as there have been computers, there have been computers that don&amp;#039;t run fast enough,&amp;quot; Myers tells PM. &amp;quot;When there&amp;#039;s more computer power available, there&amp;#039;s more desire to use it.&amp;quot; He adds: &amp;quot;[Progress bars] would stop only if human progress stops.&amp;quot; I can&amp;#039;t quite tell if this is an optimistic view of the future or an incredibly depressing one, but I suspect it&amp;#039;s right. "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/technology/gadgets/how-to/a7417/why-the-progress-bar-is-lying-to-you/>