It takes the average consumer 233 hours - that is, nearly ten whole days - to purchase a product online after initially being targeted by an advert, according to a study by Rakuten Marketing that examined display advertising and retargeting patterns in the UK. This article is copyright 2014 The Best Customer Guide.

The study showed how much the time to sale differs across sectors, with fashion being the most considered purchase at 282 hours and travel buys surprisingly the least, at 176 hours.

A proportion of shoppers however, do buy immediately after being retargeted with an ad. 14.4% of sales across the travel sector are made straightaway, compared to 8.3% of fashion purchases and 11.7% of luxury fashion buys, suggesting that luxury shoppers are more impulsive than high street customers.

Typically, the shopping journey will involve 2 to 3 engagements with the brand's ad before a product is purchased. In addition Rakuten has found globally that people who engage with an interactive banner return, and convert up to 44% faster, than those who just click. This metric of 'engagement' goes beyond a click, tracking the interaction between the consumer and an ad. It captures actions from scrolling, hovering or even watching a video within an ad.

The shopping journey transcends PC, mobile and tablet for all sectors. While desktop is the device where the final purchase is most likely to happen, tablet devices are likely to drive around 10% of sales, particularly across luxury fashion, travel and children's products. Children's products, for example, was the category that involved the fewest engagements to purchase and with the highest volume of purchases made on tablet devices, as busy parents have less time to browse.

"Customers are making increasingly considered shopping decisions. Brands therefore need careful planning to target consumers even more effectively, truly taking advantage of each engagement and reducing the delay to purchase," said Rakhee Jogia, director of display for Rakuten Marketing. "With sales taking place across numerous channels, over a number of days, it's become ever more challenging for brands to keep the interest of distracted consumers. With the help of data insights and more creative placements, brands can deliver display campaigns that increase conversion levels."