Examples of Variability

Examples of the demand dilemma abound, as can be seen by looking at Web site traffic. Every online company—Facebook, Google, and eBay, but also, say, AgathasFruitJams.com—has its own distinctive pattern of variable demand, as recognizable as a heart murmur is to a cardiologist based on a glance at an electrocardiogram (EKG). This variable demand is a composite of multiple individual decisions, such as “I think I’ll post my photo with Betty and Wilma now.” Analyzing such traffic tells us roughly what the demand is on customer-facing Web server resources and the computing equipment supporting them, which in turn acts as a proxy for business demand volume. A currently free, easy-to-use source of such data is Alexa.com, the “Web Information Company,” an Amazon subsidiary. You can receive your company’s EKG in a matter of seconds by typing in its domain name (if it is large enough to track).

Alexa provides a variety of metrics for thousands of Web sites, such as global users and average page load times, but the one that is the best proxy for overall demand volume is the “estimated percentage of global page views,” which Alexa can report on at various time scales. Every time a Web surfer visits a page on a Web site counts as a page view. Although a page view on YouTube may require more compute, storage, and network resources than one on Twitter, and a page view on Amazon.com may generate more or less revenue than one on AstonMartin.com, it is not the variation ...

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