The systems and methods described herein enable measurement of the exposure of a user to advertising campaigns across different channels (e.g., websites accessed by web browsers of laptops, desktops, or mobile computers, electronic readers or tablets, applications on mobile devices, and the like) and credit the exposure of the user to the advertisement to a specific advertisement in the campaign along with subsequent shopping events generated by the user, such as visiting product detail pages, visiting the read all reviews page for a product, adding a product to a wish list, adding a product to a shopping cart, subscribing to a product through an online subscription service, and/or purchasing a product.