Arbitron explains how US Census will affect estimates

The US Census will attempt to count every person in the United States this year. But in the monthly Portable People Meter (PPM) conference call, Arbitron’s Senior Demographer, Dan Estersohn, explained how long it will take for the new census data to be reflected in radio market estimates.

First off, Esterson said to expect no big surprises, but rather “more of the same” from the 2010 Census. That means an increase in Hispanic population estimates and a decrease in the proportion of “other” (not Black or Hispanic) demos under age 45.

“While we’re talking in generalities, market-by-market can certainly vary,” Estersohn noted.

Arbitron’s metro population estimates come from Claritas, which uses US Census data, but then adjusts annually for population trends. So, by the time the official Census data comes out, Claritas will already be adjusting to include population changes since the time that the Census data was collected this year.

Estersohn said the first data from the Census Bureau is only partly useful for projecting population estimates. In late December 2010 the Bureau will release counts of the total population of each state, as required by the US Constitution, but without age, sex or ethnic detail, nor even population estimates by county. So that is of limited use.

“About a year from now, local counts of persons by race and Hispanic origin will be released on a state-by-state basis, starting probably in late February and going through March. The only age data, though, will be 0+ total population or Adults 18+. No gender breakouts in these data. This is a requirement by law that these counts have to be released by March 31, and so they will be in that order,” Estersohn explained.

The complete set of Census data, including all of the gender, ethnic and age breakouts, will be released on a state-by-state basis in the spring and summer of 2011. That will not leave Claritas time to incorporate the new age/sex detail, but there will be new total population and race estimates for Arbitron markets for the Fall 2011 survey period. Estersohn said the full impact of the new Census data could be reflected in the Arbitron market estimates, including compisition by age and gender, as soon as the Winter 2012 survey period. But, he added, that would already be updated by Claritas to 2012 estimates extrapolated from the 2010 Census data.

During the monthly PPM conference call, Arbitron officials were again patting themselves on the back for another month of improvement in sample composition. The Designated Delivery Index (DDI) was over 100 on average for the January report, with Sr. VP Bill Rose proudly noting that the DDI average was over 90 for all 18-34 demosw, with Black 18-34 at an all-time high of 98. Hispanic 18-34 was at 91 and “other” 18-34 at 94.

Remember the old rule of thumb that Arbitron was pushing for advertisers that 70 gross ratings points in PPM can equal 100 under the previous diary measurement for a market? That’s now been refined on a market-by-market basis, with an average now of 84 GRP being the same as 100 GRP under the previous diary measurement.

Click here to download the one page pdf summary.

For market-by-market details, in Spanish as well when pertinent, Arbitron has a whole webpage of Target Rating Point conversions. Click here for that.

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