Quick, which of the many shopping channels showed the greatest growth during the 2003 holiday period?

You'd be wrong if you said it was retail, catalogs or the Internet. It was all of them combined.

Yes, the single greatest growth was in the number of consumers who shopped in multiple channels, according to DoubleClick Inc.'s third annual survey of holiday season shopping. That percentage jumped to 65%, a nine-point increase over the prior year.

In contrast, catalog use experienced only a 2% increase to 27%, and retail actually suffered a 2% decline — to 85%.

Internet use grew by 2% to 66%, but consumers showed that they're getting savvier. Of those polled, 84% said they abandoned online shopping carts last year because of additional costs like shipping and handling. That's up from 78% in 2002.

Shoppers are also getting more fickle. Almost a third said they had changed their minds about a product during their visit online, compared with 19% in 2002.

DoubleClick reported that separate research from its SiteAdvance unit revealed that for every dollar sold online during the season, over $6 was abandoned in a shopping cart.

But there is some good news — 92% said they were receptive to free shipping offers as a way of luring them back to a shopping site.

Of those surveyed, 36% shopped in two channels — retail and Internet. And 24% used all three.

According to DoubleClick, the largest spenders were those who shopped in all three of the channels listed above. They spent $1,000 during the season, and 35% of them spent 33% more than the average single-channel shopper.

Their reasons for splurging? They were as follows: More people to buy for (49%); special offers or discounts (42%); economic reasons (37%); and more interesting gifts (36%).

Triple-channel shoppers tended to be female. And they spent an average of 17% more than dual-channel consumers. Retail-Internet buyers were most often men.

But to browse in a channel was not necessarily to shop in it. The survey showed that 57% browsed in one channel and purchased in another.

How did that work? DoubleClick found that 43% of the multichannel shoppers who browsed on the Internet went to retail stores to make the actual purchase. Another 19% reported that they browsed in catalogs and shopped in stores. Finally, 16% said they browsed in stores but bought online.

The report is based on data from 1,000 respondents who were interviewed in December and January. The survey was directed by Beyond Interactive and conducted by Greenfield Online.

Meanwhile, DoubleClick noted in a separate report that it served 203.8 billion online ads during the fourth quarter, a 43% increase over the third quarter. Response rates or clickthroughs declined, most likely because of increased ad volume.

But view-through rates, which quantifies users who convert within 30 days of viewing an ad (but do not click through) are higher than clickthrough rates.

And clickthrough rates for rich media stood at 1.24%. In comparison, catalogs pulled an average response rate of only .37%, according to Abacus, a DoubleClick subsidiary.

Rich media, which consists of dynamic ads, pop-ups and any ad that uses Flash technology, is growing in popularity, DoubleClick noted. Almost 40% of the ads served during the fourth quarter used rich media . That figure represents a 60% increase over the second quarter.