• by David Goetzl  @dgoetzl, June 30, 2009

Nielsen told clients Tuesday it would increase by 25% the size of its Local People Meter samples in each of the country's two largest markets. By next summer, the sample sizes in New York and Los Angeles will rise from the current 800 to 1,000.

The markets together represent 11% of U.S. TV homes and account for 20% of the spot ad business, Nielsen said.

Nielsen in a client note said the larger samples "will improve the statistical reliability of the ratings data in these two very diverse and complex" DMAs. The increase in the samples will take 13 months to complete, with batches of 50 homes being added in each market at four separate intervals.

In New York, the additions start Feb. 4, 2010 and follow on April 1, May 27 and July 29. In L.A., the increases begin March 4, 2010, followed by April 29, July and Aug. 26.