Houston, We Have A Sample Performance Index Problem
April 19, 2011 at 9:01 AM (PT)
ARBITRON sent a letter to HOUSTON-GALVESTON subscribers this morning, with "Information About Sample Performance Index in HOUSTON-GALVESTON ARBITRON eBook, HOLIDAY 2010-FEBRUARY 2011," informing them of a "re-posting" of data, due to an "overstatement."
"ARBITRON includes in each PPM Radio Market Report (ARBITRON eBook) a Sample Performance Index (SPI) for Persons (Persons SPI) and Households (Household SPI) in the Sample Summary section of the report.
The Persons SPI and Household SPI percentages listed in the HOLIDAY 2010 through FEBRUARY 2011 HOUSTON-GALVESTON ARBITRON eBooks have been updated and re-posted. HOUSTON-GALVESTON subscribers who previously referenced this information should reference the SPI information currently available in the HOLIDAY 2010 through FEBRUARY 2011 ARBITRON eBooks. (HOUSTON-GALVESTON SPI percentages originally listed for the HOLIDAY 2010-JANUARY 2011 report periods had been overstated by 0.2 to 0.4 percentage points.)
In addition, HOUSTON-GALVESTON SPI percentages listed for SEPTEMBER 2010 through DECEMBER 2010 may have been overstated by 0.2 percentage points or less.
SPI information in the MARCH 2011 HOUSTON-GALVESTON ARBITRON eBook is not affected. SPI information in markets other than HOUSTON-GALVESTON is not affected for any report period. Audience estimates are not affected for any market or report period."