ATLANTA – Many U.S. Internet service providers have now fallen in line with their international counterparts in capping monthly residential broadband usage. A new study by a Georgia Tech researcher, conducted during an internship at Microsoft Research, shows that such pricing models are often difficult for home broadband users to manage.

Home users, the study found, tend to be uncertain about their remaining bandwidth balances and about the amounts of bandwidth they and other users in their home require. These uncertainties can force difficult choices on users.

Marshini Chetty, a postdoctoral researcher in Georgia Tech’s School of Interactive Computing, interviewed 12 households in South Africa, a country in which broadband caps were universal until February 2010. Typically, the caps set by South African ISPs are severe, with some plans offering only 1 GB of data per month. At the time of the study, the caps ranged up to 9GB of data, far lower than the 150GB – 250GB caps typically set by U.S. providers. Because customers had few, if any, ways to monitor Internet usage, their access often would be cut off in the middle of an online activity.

Chetty and her collaborators found South Africans had built coping mechanisms into their daily lives to manage their online activities under the caps. Some would routinely “top up” their accounts (pay additional fees for incremental cap increases), and others would visit family members to use their Internet accounts or switch from desktop connectivity to smartphones.

“People’s behavior does change when limits are placed on Internet access — just like we’ve seen happen in the smartphone market — and many complain about usage-based billing, but no one has really studied the effects it has on consumer activity,” says Chetty, who earned her Ph.D. in computer science from Georgia Tech in 2011. “We would also hear about people ‘saving’ bandwidth all month and then binge downloading toward the end of their billing period.”

Customers were often unable to determine which applications were eating up their bandwidth. Some were unaware that streaming video or downloading songs consumes much more data than normal web browsing; others did not know whether background applications such as automatic software updates counted against the monthly cap.

Capped Customers More Vulnerable to Viruses
“We were surprised to learn that many of the households we studied chose not to perform regular software updates in order to manage their cap,” Chetty says. “This activity can be benign for some applications, inadvisable for others and downright dangerous in certain cases. For example, not installing security patches on your system can leave you vulnerable to viruses and other sorts of cyber attacks.” Chetty suggests that the frequency of such risky behaviors among the broader population of metered/capped Internet users should be assessed via follow-up scientifically representative surveys.

Finally, in households with multiple Internet users, heads of households can have difficulty managing overall activity when they are not fully aware of each member’s Internet use. As with other consumable resources in a household, from milk to hot water, the apportionment of “fair” amounts of bandwidth reflects family practices and requires a fair bit of nuance, varying by family style and composition.

“As ISPs move more toward usage-based pricing, we need to keep in mind the reactive behaviors that consumers adopt and the consequences of those behaviors. Because when you have broadband caps, you will use the Internet differently,” Chetty said. “This study was performed in South Africa, and although the caps are higher in the United States, there are still instances where people are hitting them. So if you’re going to have caps, you should empathize with your users and offer ways for customers to see how their data are being used and who is using them.”

More bandwidth monitoring tools are becoming available from ISPs, within operating systems and from third parties; this is one of the first academic studies that systematically reveals why there is a demand for such tools and why they are important to users.

The study’s findings are summarized in the paper, “’You’re Capped!’ Understanding the Effects of Bandwidth Caps on Broadband Use in the Home,” which Chetty will present on May 10 at the 2012 ACM SIGCHI Conference on Human Factors in Computing Systems (CHI 2012), held May 5-10 in Austin, Texas. Chetty’s coauthors include Beki Grinter, professor in the Georgia Tech School of Interactive Computing, and Richard Banks, A.J. Bernheim Brush and Jonathan Donner from Microsoft Research.