• by David Goetzl  @dgoetzl, August 3, 2010

Fighting some perceptions that its emerging set-top-box (STB) measurement service may draw data from a limited base, Rentrak said Tuesday it has expanded its pool significantly. 

  The company said a wider agreement with Charter Communications allows it to prune data from boxes across the cable operator's footprint. Charter serves 4.8 million homes, according to statistics from the cable trade group.

Some subset -- not disclosed by Rentrak -- of homes with digital set-top-boxes will be usable by Rentrak for both its national and local-market STB-based viewership services.

Charter households will be combined with data from some homes served by Dish Network and AT&T.

The Charter data is anonymous and offers insight into both linear and time-shifted viewing.

For some time, Charter had been offering STB data from 300,000 homes in the Los Angeles market to Rentrak and other data providers.

Rentrak's expansion into the STB-based ratings arena was enough to prompt a question to Nielsen CFO Brian West Friday of whether its forays could impact Nielsen's business. West downplayed any threat, saying Nielsen was taking a different tack.