One measures the variation of bandwidth over time to reveal whether a service provider is slowing down or speeding up connections. Several independent Web sites can provide speed results, but the results can vary drastically. Using an independent test will not isolate the last link, but it will reveal information about how well the service provider is connected to the larger Internet. Glass said, giving a higher priority to tests for speed. “There are a number of providers that put their thumb on the scale,” Mr. in Laramie, Wyo., said that many customers did not trust their service provider’s test and instead worked with other speed tests available on the Web. If the provider cannot speed up a slow connection, a user might want to make a switch.īrett Glass, the owner of Lariat, an I.S.P. Checking this last connection will usually pinpoint any problem that a service provider can fix. Most service providers offer a tool so their customers can test the performance inside the network, the last link in the long chain from a computer on the desk to a service provider’s distant server. The simplest test involves downloading a big file, counting the seconds, and then dividing to compute the raw bandwidth in megabits per second. Any extra latency gets compounded because you have many, many stages.” “You click on a link and you end up setting dozens of connections. “Even in Web browsing, pages are getting more complicated,” Professor Odlyzko said.