83% of adults cited past experience with a brand as the most important factor in their purchase decisions. Quality and price — issues often promoted in advertising — ranked second and third. Personal recommendations came in fourth, highlighting the importance of word of mouth.

Another strong influence: ratings in Consumer Reports, cited by 15% of adults in the Roper survey. (The ad-free magazine scored as the “most trustworthy and objective” media outlet for information on consumer products in a 2005 American Demographics survey.)

Roper’s findings came from its syndicated research based on in-person interviews in August and September with 2,000 adults.

Among influencers, there’s no denying the role of advertising. Advertisers last year spent $2,355 per U.S. household as they bid for their slice of consumer spending, according to Advertising Age’s analysis of ad data from Universal McCann’s Robert J. Coen. The average household in 2005 spent $46,409 on goods and services, according to data released this month by the Bureau of Labor Statistics.