How the data was measured. Possible values include:
- Measured - The data for the metric was directly measured by client code that either Google controls or with which Google has intimate familiarity, or it uses OMID data from client code that was certified by Google or IAB Tech Lab.
- Provided - The data for the metric was measured on the client by a third party who then provides the data to Google over a server-to-server integration, or it uses OMID data from client code that was not certified by Google or IAB Tech Lab.
- Inferred - The data for the metric was inferred using sound judgment, however it was not directly measured on the client. The inferred metric may originate from Google or a third party.
