Select metrics you need in each channel to help you gain insight into your campaigns. They should measure your success in achieving your goals. How do you do this? You could, for example measure adoption and engagement, collaboration and rich media consumption (video, podcasts), and device consumption (desktop or smartphone).
In the selection of metrics you use, try to be consistent in your choice across each of your communication channels. By doing this you are not looking at channels in isolation – you are getting consistent insight into engagement across all channels, allowing you to make decisions based on these insights