HBO, Showtime and Starz are disputing a report issued this week from research firm NPD Group that found a decline in customers for premium television networks, reports Variety.

As previously reported, the study found that the number of households subscribing to HBO and other pay-TV channels slipped 6% during the past two years. At the same time, Netflix and other online video services have seen subscriptions grow by 4%, according to the study.

The pay-TV networks said the findings were wrong.

“The (NPD) study does not accurately reflect actual subscriber counts,” Showtime said in a statement. “While it is true that video services like Netflix have gained, so too have premium cable channels.”

HBO said that NPD’s research was “simply incorrect.” A representative told the publication that both HBO and Cinemax have grown their subscriber bases.

HBO, Showtime and Starz cited SNL Kagan’s estimates for premium-TV channels, which found that penetration of the three networks and Cinemax all grew from March 2012 through September 2013, the story notes.

An NPD spokesman said the company was reviewing the research, but declined additional comment.