A new study from the Pew Internet Project casts light on the love-hate relationship many Americans have with e-commerce. In response to the survey, 78 percent of U.S. Internet users said that online shopping is convenient, and 68 percent said it saves time. Yet, 75 percent said they don’t like giving out personal information like a credit card number over the Internet. The security risks, real or perceived, are hampering the growth of the Internet economy, said John Horrigan, associate director of the Pew Internet Project and author of the report.