A new U.S. study suggests advertising icon David Ogilvy’s decades-old theory on costly tv commercials and their lack of effectiveness is correct.

Ogilvy wrote in his book, Ogilvy on Advertising, that although he had no evidence to prove it, he, nevertheless, suspected the more money spent on producing tv commercials, the less effective they are selling products.

Research Systems, a market research firm in Evansville, Ind., recently tested Ogilvy’s theory using 56 new and established tv spots for six categories of products.

Research Systems results show the more effective sales-producing advertisements cost less on average and the poorer-performing spots cost more.