Nielsen has initiated tests with Time Warner Cable, Cablevision Systems and two programmers to try to measure live TV viewing on the cable operators' iPad applications.
The effort is still in "an R&D stage," said Matt O'Grady, Nielsen's executive vice president of media audience measurement.
"Right now, iPad streaming is not having an impact on ratings," O'Grady said. "But we're taking [the project] dead seriously because our clients need to know what the viewing is on tablet and smartphone platforms."
O'Grady declined to identify the two media companies participating in the test.
Time Warner Cable has said its TWCable app for iPad has been downloaded more than 600,000 times since it was released March 15, while Cablevision said last week its Optimum app for iPad topped 200,000 downloads since its early April debut.