Technologies are generally described to adaptively sample merchant sites linked to payment transactions to gain insight into activities, interactions, and behaviors of visitors within the merchant site. In some examples, a payment network may define a virtual perimeter that represents an area of the merchant site in which to capture selected measurements. The virtual perimeter and measurements may be transmitted to a client application being executed or executing on a portable device associated with a visitor. The client application may capture the measurements and transmit the captured measurements as tracking data to the payment network upon detection of a presence of the portable device within the virtual perimeter. Payment data processed by the client application may also be transmitted to the payment network. The payment network may process the payment and tracking data to perform a business intelligence analysis associated with the merchant site.
