Appearing to clash with a study issued just last week by Nielsen Research indicating that fewer than 1 percent of viewers use DVRs to watch programs at a later time, Horizon Media issued its own study Wednesday concluding that DVRs are permanently altering viewing habits. According to the Horizon study, details of which were published Tuesday on the Advertising Age website, 11 fall season programs were regularly "time-shifted" by viewers this season, versus three last year. They included Fox's House , which was watched on DVRs by 5.04 million viewers. ABC's Grey's Anatomy was time-shifted by close to 4.97 million viewers. NBC's The Office was recorded by 3.81 million. If accurate, the figures are significant. House averages a same-day audience of about 13 million; Grey's , 16 million; and The Office , 9 million.