Online sales grew 13.9% from Nov. 1 to Dec. 31 compared with the holiday period in 2013, according to IBM Corp.’s Digital Analytics Benchmark report. That’s greater than the growth posted in the comparable period in 2013, which saw 8.5% sales growth. The benchmark pulls data from 8,000 brands and 35,000 e-commerce clients, according to IBM; it does not report dollar sales.

The first of several holiday season estimates that will be trickling out in the weeks ahead, this one falls into the middle of pre-season estimates. Before the gift-giving frenzy began, estimates had ranged from 10% (Adobe Systems Inc.) to 16.6% (eMarketer Inc.). Forrester Research Inc. projected holiday sales growth at 13% and comScore Inc. at 16%. IBM did not make a full-season prediction.

The new data from IBM show some sales days fell below expectations, possibly a reflection of such major retailers as Amazon.com Inc. and Wal-Mart Stores Inc. launching their Black Friday offers well before Thanksgiving weekend. During the key Thanksgiving-to-Cyber Monday period, IBM projected web sales to increase 15.6% on Thanksgiving, 13.0% on Black Friday and 15.8% on Cyber Monday. Sales growth on all three of these days came in under expectations, IBM says. Web sales on Thanksgiving Day grew 14.28%, grew 9.48% on Black Friday and 8.5% on Cyber Monday. “Growth was less about the key shopping days,” says Jay Henderson, director of IBM SmarterCommerce. “Instead promotions started earlier and lasted longer.” An earlier IBM report showed that web sales on the weekend before Thanksgiving were up 18.7% over the same weekend in 2013, likely a sign of the impact of early sales during the recent season.

Consumers spent less per order than last year, the IBM report says. The average order value during November and December was $119.33, down 8% from the same period in 2013, which IBM attributes to consumers shopping for bargains.

Mobile devices played a larger role in holiday shopping, accounting for 45% of all online retail traffic during the season, up 25.5% from a year ago. Smartphones accounted for more traffic than tablets, 31.2% versus 13.4%, but tablets accounted for a greater percentage of sales. Transactions on tablets accounted for 13.4% of total web sales and smartphones for 9.1%. IBM says sales on mobile devices were up 27.2% year over year during the holidays. The average order value for orders placed on mobile devices was $104.82 versus $125.12 for orders placed from desktop and laptop computers.

IBM also tracked the average order value of sales resulting from traffic coming from Facebook and Pinterest. The average order value for consumers coming from Facebook was $101.38 and $105.75 from Pinterest.