Combining measurements based on beacon data

A computer readable storage medium storing instructions that, when executed by one or more processing devices, cause the one or more processing devices to perform operations comprising:

• accessing usage data representing the access of a set of resources on a network, the usage data based at least in part on information received from client systems sent as a result of beacon instructions included with the set of resources;
• determining, based on the accessed usage data, a first set of usage data representing access by client systems classified as a first type;
• determining a count of unique visitors accessing the network resources from the first type of client systems based on the first set of usage data;
• determining, based on the accessed usage data, a second set of usage data representing access by client systems classified as a second type;
• determining a count of unique visitors accessing the network resources from the second type of client systems based on the second set of usage data, wherein determining the count of unique visitors accessing the network resources from the second type of client systems comprises:
• determining, based on the second set of usage data, a first subset of data representing information about accesses to the resources by the client systems classified as the second type associated with persistent beacon identifiers, wherein the persistent beacon identifiers are associated usage data collected over a duration that exceeds a persistence threshold,
• determining, based on the second set of usage data, a second subset of data representing information about accesses to the resources by the client systems classified as the second type with non-persistent beacon identifiers, wherein the non-persistent beacon identifiers are associated usage data collected over a duration that does not exceed a persistence threshold,
• determining one or more adjustment factors based on the first subset of data, and
• determining a count of unique visitors accessing the set of resources from the client systems classified as the second type based, at least in part, on a count of accesses by the client systems classified as the second type and associated with persistent identifiers, a count of accesses by the client systems classified as the second type and associated with non-persistent beacon identifiers, and the determined adjustment factors;
• and
• determining a total count of unique visitors accessing the network resources from the first and second types of client systems based on data representing a usage overlap of devices of the first type with devices of the second type.