The “Amazon effect,” or the impact of digital on traditional retailing, is forcing retailers to step up their game.

As retailers strive to incorporate new services to satisfy shoppers both in-store and online, their first priority is adding services to compete with the promise of free shipping.

Seventy-five percent of online shoppers are “greatly impacted” by free shipping when they make purchase decisions — no doubt due in large part to the Amazon effect, according to the “2016 Home Delivery and Final Mile Services Report,” from AlixPartners.

In fact, the maximum acceptable delivery time among omnichannel shoppers has declined 13% since 2012 to 4.8 days, according to data.

While retail segments struggle to meet these expectations, many are taking steps to become more competitive.

The footwear segment is most aggressive in this category — so much so that footwear companies now feature the shortest average delivery time and the lowest average free shipping threshold. Specifically, the category’s free shipping minimums range between $24.99 and $100, and deliveries end up in…