Here's what drove online holiday sales growth

The numbers are in and one specific device clearly served as a major catalyst for increased e-commerce sales during the 2015 holiday season.

According to the MarketLive 2015 Holiday Flash Report, smartphone revenue during the just-completed holiday season (Nov. 23, 2015 – Jan. 3, 2016) increased 50%. Overall e-commerce revenue grew 8% during that period.

In terms of online visits, smartphone growth (19%) slightly tailed overall visits (21%). However, smartphone conversion rate rose 8% to 1.3% from 1.2%. Meanwhile, overall conversion rate plunged 13% to 2.7% from 3.1%.

In addition, average order value (AOV) increased at a higher rate for smartphones than for overall e-commerce orders. Smartphone AOV rose 9% to $140.63 from $129.06. This brought smartphone within less than $8 of overall e-commerce AOV, which climbed 6% to $147.24 from $139.24.

According to MarketLive analysis, further improvements to the smartphone experience will be crucial in 2016. With solid gains to show for their 2015 mobile optimization initiatives, MarketLive says retailers should feel confident in making further mobile investments during 2016.