From Harker Research - Wireless Arbitron

Arbitron Still Playing Wireless Catch-Up

The proportion of US households who have abandoned landlines in favor of wireless continues to grow. Yet Arbitron’s diary keepers and PPM panelists remain predominantly landline households.
According to the latest government numbers, in the Fall 0f 2009 25% of households were cell phone only, up from 20% in Fall of 2008. (Click on chart to view.) Unfortunately, Arbitron’s goal for 2010 falls well short of even last year’s numbers.

The company hopes to have cell phone only people comprising 15% of diary keepers and 20% of PPM panelists year’s end.
In other words, by 2011 Arbitron hopes to reach the 2009 numbers.
According to the CDC (pdf here):
Preliminary results from the July-December 2009 National Health Interview Survey (NHIS) indicate that the number of American homes with only wireless telephones continues to grow. One of every four American homes (24.5%) had only wireless telephones during the last half of 2009.
The report goes on to document a new phenomenon, households who have a landline, but don’t use it. Some telephone companies allow households to pay a minimal fee to keep a landline for emergency purposes only.
The CDC notes:
One of every seven American homes (14.9%) had a landline yet received all or almost all calls on wireless telephones.
In response, Arbitron has created a new category of participant, those who have a landline, but primarily use a cell phone, what they call a cell phone household (not to be confused with a cell phone only household).
Arbitron’s 2010 year end goal is to switch 5% of their sample to cell phone in addition to the 20% cell only for a total of 25%. So a year after the government tells us that about 40% of households were cell phone primary or only, Arbitron’s sample goal will be 25%.
In Arbitron’s latest PPM report, the company also noted that it expected its PPM 18-34 sample to reach about 40% cell phone (primary+only) by the end of 2010. According to the government, about 60% of people in this demo were already in cell phone households in Fall of 2009.
Arbitron failing to recruit more cell phone participants is troubling. As we reported in March of 2009, Nielsen found significant differences between landline and cell only households. As we noted then:
Nielsen's finding that 20% of listeners live in cell phone only households and that these people spend 20% more time with radio is significant. Nielsen found that cell phone only homes listened to radio an average 23 hours per week, while the total sample spent just more than 19 hours listening to radio. Those younger households also tuned in to an average of 3.5 stations vs. less than three for landline homes.
So we could see higher numbers if Arbitron made a greater effort to recruit cell only households.
The CDC also noted:
Hispanic adults (30.4%) were more likely than non-Hispanic white adults (21.0%) or non-Hispanic black adults (25.0%) to be living in households with only wireless telephones.
Both Urban and Hispanic stations should be particularly upset that Arbitron is taking so long to recruit a representative sample of cell only households.