淘宝网上添加商品到购物车时，弹出窗口显示购物车里面的状态。
淘宝网购物车
不结账，继续购物的时候，淘宝不给任何购物车状态提示，除非你点击顶部购物车链接或者再次添加宝贝到购物车，才能知道购物车里面到底有多少东西、要花多少钱。
当当网上在商品页面点击购买后直接进入购物车，不结账，继续浏览，会发现在当当网顶部有购物车状态提示有多少个商品在购物车里了，但是不告诉你总共多少钱。
当当网购物车带着走
altrec上添加商品到购物车的时候，顶部动态打开窗口给出细节提示。
altrec的购物车提示
关闭后缩小为简单的购物车状态提示，信息包括物品数目、总金额。继续浏览购物时，购物车状态提示一直跟随，并且一直提醒免运费。
altrec的购物车站台跟随
当当网与altrec.com的这种跟着用户走的购物车叫做Perpetual shopping carts，（不知道学名叫什么，我把他叫做随身购物车，或者贴身购物车？）根据Marketing Sherpa的调查64%的在线零售商认为这种购物车对于提高转化很有帮助，而且altrec.com这种高级的购物车状态跟随比当当的这种简洁版效果要好。
Perpetual shopping carts: these come in a variety of ‘flavors’ and not all are created equal. The data is limited, but it appears that carts which ‘ride along’ with the shopper as they move through the site have a significant impact on conversion. This varies by the type of perpetual cart. Some simply show a dollar total that changes dynamically with purchases, while others may show some or all of the following; product details, thumbnail images, estimated shipping costs and recommended accessories/related products. While 38% of our sample employ some version of the perpetual cart, the vast majority fall into the simpler category, which has a positive but lesser effect than the enhanced versions.
同样在MarketingSherpa的2009 Ecommerce Benchmark Report里面，分析师和营销人员都认为Perpetual shopping cart对于减低购物车放弃率有很好的帮助。
Shopping-Cart Abandonment
电子商务网站要提高转化率，流程里外优化都重要。谁对这方面有研究的？欢迎分享、探讨下。
