Online sales are expected to increase by 53 percent this holiday season, compared to the same period last year.

The predictions come from Performics, an index of search campaigns designed to monitor the growth of paid search advertising. The company is a marketing division of DoubleClick.

The company announced Monday that marketers could expect fourth quarter sales to equal sales of the first two quarters of 2006. The company said, since that should hold true for budgeting and marketing costs, marketers can combine their first and second quarter budgets to forecast their fourth-quarter spending.

Performics reported a growth in search spending, impressions and displays increasing by nearly 50 percent, while active keywords grew by 58 percent and total clicks grew by 32 percent this year, compared to last year.

Most of the growth is due to increased knowledge and sophistication in search engine marketing, according to the forecast. Increased competition for higher-priced and more popular keywords and mining of the long tail of key words have helped marketers balance out their keyword portfolios, according to Performics. Cost per keyword increased only 14 cents, or less than .5 percent, from first quarter averages, showing that marketers are improving search engine campaigns.

Cam Balzer, director of search strategy for Performics, said that "program managers are harnessing the full value of search" and realizing that aggressively managed online campaigns -- that drive online sales, offline sales, increases brand awareness and maximizes search budgets -- are critical to overall marketing success."

"This potentially means big business for the final quarter of 2006 and the upcoming holiday season," he said.