The Philly PPM in-tab explanation


Yes, in-tab numbers for PPM were down for Week 1 of March in Philadelphia (4/2/08 RBR #65). After checking into it, Arbitron Sr. VP Thom Mocarsky says that was a result of the company’s efforts to improve performance in Persons 25-34, as promised to broadcasters.

“As we have announced several times in PPM monthly update calls, we have been awaiting completion of sampling software that would permit sample matching based on a Basic Sample household’s 25-34 status.  Previously this matching capability was limited to households with persons 18-24, but starting in March we expanded this to include the 25-34 matching in all PPM markets other than Houston.

We started the matching process in week 1 of the March PPM survey. Some installed households that did not match the Basic sampling point on 25-34 status were de-installed and we start to replace them with matching 25-34 households. The goal of this process is to improve both sample delivery and sample proportionality for the 25-34 age group in PPM panels.  The planned de-install and replace process did have an impact on the average daily in-tab, but at 1,686 persons 6+, it remains well above our goal of 1,530 persons,” Mocarsky said in an email to RBR/TVBR.

He said the process creates a temporary increase in panel turnover, which in turn temporarily reduces average in-tabs.

“It is Arbitron’s goal to deliver overall samples as closely as possible to the 100 DDI targets.  Now that we have the matching capability for persons 25-34, we have started the process of reducing sample over-delivery, through normal panel attrition, to better align our actual delivery with those targets,” Mocarsky said.