subject: Signature Variables To Create Realistic Distributions [print this page] As the name suggests, online behavior variables deal with behavioral differences between users. Some users, for example, read Web pages and navigate Web sites faster than others; we call this difference User Interaction Speed. Interaction speed is very relevant because, in a given amount of time, a fast user is able to go through more Web pages than a slower user. This results in more requests and therefore a higher load, for the Web site under test. These variables are used in combination with other Web site Usage Signature variables to create realistic distributions.
Lets say, for example, that the average viewing time for a Web sites home page is 53 seconds. Although this number is extremely useful, its just an average. A slow visitor unfamiliar with the Web site may spend 2 minutes on the home page, while a fast visitor who is already familiar with the site may stay on it for just a couple of seconds before navigating to another page. A load test that does not consider these variations is simply not realistic and will generate misleading results. By combining the average viewing time with the user interaction speed variable and taking into account the users familiarity with the Web site, you create loads that simulate real usage much more accurately.
In the absence of log files, or the lack of time or resources for detailed log analysis, you can leverage some of the metrics and statistics collected by companies such as Nielsen//NetRatings, Keynote, or MediaMetrix. Nielsen//NetRatings, for example, provides data on average page viewing times and user session duration based on a very large sample space of users and Web sites. Although these numbers are not from your specific Web site, they can work quite well as first approximations.
