1. A computer-implemented method comprising: receiving, by a computer-based system capable of linking customer information, customer information of a first set of customers from a first entity, wherein the customer information comprises personally identifiable information and first entity customer attributes for the first set of customers; receiving, by the computer-based system, personally identifiable information for a second set of customers from a second entity; identifying, by the computer-based system, common customers between the first set of customers and the second set of customers using the personally identifiable information; sending, by the computer-based system, a list of a third set of customers to the second entity, wherein the third set of customers comprises the common customers and a plurality of non-common customers from the second set of customers; receiving, by the computer-based system, second entity customer attributes of the third set of customers from the second entity; linking, by the computer-based system, the first entity customer attributes and the second entity customer attributes of the common customers using the personally identifiable information; receiving, by the computer-based system and from the second entity, test results from an advertising campaign involving the common customers and the non-common customers; removing, by the computer-based system, common customer test result data; and transmitting, by the computer-based system, common customer test result data to the first entity.