It wasn’t long ago that many local television stations were enraged over the rollout of Nielsen's local people meter to replace its decades-old and not very accurate diary measurement system.

Facing viewership declines, stations squawked that the LPM undercounted viewers and that its sample was weighted against minorities. Nielsen stood its ground, and the rollout proceeded.

Now Arbitron is in the process of rolling out its portable people meter, with the new, more accurate electronic system for tracking radio listening set to go live next Wednesday in New York, Los Angeles, Chicago and a few other markets.

It too is facing protests, and it too is proceeding.

The beefs are similar. Spanish-language and black stations in particular complain that the new system undercounts their listeners. Some radio station groups have gone so far as to drag in the Federal Communications Commission and local political groups to investigate the PPM and its methodology. New York attorney general Andrew Cuomo has undertaken his own investigation.

These protests hardly come as a surprise. The PPM had already met considerable resistance when it was rolled out in Philadelphia and Houston, where it went through extensive testing and modifications.

For their part, media buyers consider the PPM a huge improvement because it automatically tracks which stations people are exposed to, and passively, not relying on people to remember what they listened to, as the diary system does.

“The PPM is a far better, more sophisticated and accurate measuring system than we’ve ever had,” says Stan Gerber, executive vice president and chief strategy officer at JL Media in Union, N.J. “But it’s upset the apple cart. People aren’t listening as much as they said they were listening.”

The controversy over the PPM comes down to ratings. Just as with the LPM and TV stations, stations can expect to see their ratings fall, which hurts ad sales and cuts into revenues.

“It’s not just Spanish or black stations affected by ratings declines. Everybody is,” says Thom Mocarsky, a spokesman for Arbitron.

But the declines are generally steeper for ethnic stations, some of which have seen declines of 50 percent or more. If the prices stations charge advertisers don’t come down with the ratings, the cost per rating point will soar.

That will be especially painful for the vast majority of ethnic stations. “Not speaking about Univision, most of the Spanish-language and urban stations are owned by small-business owners,” says Ceril Shagrin, executive vice president of corporate research at Univision. “They cannot continue to exist if their ratings go down 60 percent and the cost for the research goes up. Especially in today’s economy, this could be disastrous.”

Arbitron says it has been working with stations, media buyers and government officials to ensure there are no mysteries about the PPM or the ratings it generates.

Last November, Arbitron halted its rollout of PPMs in response to critics, taking the time to beef up its panel of respondents, including bringing in more young people and ethnic groups, who were underrepresented in some PPM tests. Arbitron now says its sample slightly overrepresents some of these groups.

“We enhanced compliance,” says Mocarsky. “We enhanced the representation of young people. In most cases, we’re beating our goals. And we’ve been talking extensively with the people who’ve raised concerns. This has been going on for more than a year.”

Still, the controversy over the PPM rollout has yet to die down.

The FCC has begun an investigation and there have been multiple hearings with local government officials, such as the New York City council. And radio station groups and associations like the Spanish Radio Association are actively calling on Arbitron to delay the PPM rollout.

That's not likely to happen. Like Nielsen before it, Arbitron is committed to pushing ahead.

“We delayed the commercialization of the PPM last year in order to address concerns,” says Mocarsky. “That was a long and costly delay but we felt it was the right thing to do. We identified a number of issues to address and we’ve done all that. Now it’s time to go forward.”