The key to valid audience-based metrics: test away, said the MRC's George Ivie. https://t.co/vE1ZpVkYg6 https://t.co/xQo7vxDDCi

The key to valid audience-based metrics: test away, said the MRC’s George Ivie. https://t.co/vE1ZpVkYg6 https://t.co/xQo7vxDDCi