In recent months, Estée Lauder's in-store sales were 5 percent higher in markets where such promotions occurred.
Mary Ellen Keating, a spokeswoman for Barnes & Noble, said no in-store sales were planned.
Part of the problem, Mr. Cassar said, is that retailers find it difficult to measure their Web sites' impact on in-store sales.
Apple Stores will be closing between 4 and 5pm to prepare, with in-store sales beginning at 5pm.
Promotions, direct sales, internet and in-store sales and tastings were some of the activities.
We also want to drive in-store sales and drive customers back to the Web.
Wal-Mart's ending of its in-store sales of handguns can lead to another chain's dropping sales altogether.
Even though their in-store sales might decline, the company may see overall gains.
And this year, many traditional retailers have overcome their fear of cannibalizing in-store sales to promote their Web sites.
For the first time in 10 years in-store sales are down slightly.