Philadelphia PPM Daily/Weekly Sample Drop Issues Addressed
April 2, 2008 at 1:25 PM (PT)
Consultant RANDY KABRICH alerted ALL ACCESS to a dramatic drop of almost 20% in-tab in the PHILADELPHIA PPM during the first week of MARCH. Specifically, the daily sample lost 56 in-tabs, and the weekly sample lost 215 in-tabs.
ALL ACCESS contacted ARBITRON, and they admitted that they should have been a bit more forthcoming on telling clients in advance what they would see when the 25-34 software program kicked in. On the surface, while it may look like repeat of the HOUSTON re-issue problem, ARBITRON says it knew this was going to happen.
This process does create a temporary increase in panel turnover, which in turn temporarily reduces the Average Weekly in-tab sample size.
ARBITRON SVP/Press & Investor Relations THOM MOCARSKY told ALL ACCESS: "The short story is that this decline in persons 6+ average daily in-tab is a result of our efforts to improve P25-34.
"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."
Sample Decrease Said To Be Temporary
MOCARSKY continued, "This process does create a temporary increase in panel turnover, which in turn temporarily reduces the Average Weekly in-tab sample size. In any given week with higher turnover rates, fewer persons will qualify for the Average Weekly in-tab sample size, which requires at least six out of seven days in-tab. Both the persons leaving the panel and those entering the panel during the week will be less likely to meet the 6-day in-tab minimum for that week. (Please note, all our sample and DDI targets are based on Average Daily in-tab sample.)
"As we have also discussed on prior sample updates, recent PPM sample sizes have been running well above the designed target levels, in part to improve the DDIs in certain demo cells while we were building the improved sampling software.
"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.
"In cases where the total P6+ sample delivery currently exceeds the 100 DDI target, customers can expect to see actual sample sizes closer move to the target. And, through our enhanced sample matching procedures, they can expect to see, over the next two months, improved 18-34 and 18-54 sample delivery relative to targets."