Shifting the focus to the time span, we may need to measure some "Interim Metrics", which give us some insight during the journey itself, as well as we need to measure some "Final Metrics" at the end of the journey to inform use if the overall initiative was successful or not. As an example, most of social media metrics and indicators such as likes, shares and engagement comments may be classified as interim metrics while the final increase/decrease in sales volume is clearly from the final category.
The web audience is changing. With mobile and voice search, the shopping journeys are becoming more fragmented and harder to predict, the attention spans are getting even shorter and the content supply is often greater than demand. Consequently, it is increasingly important to understand how your site users are interacting with the page elements, and what you can do to better engage them. What is User Engagement?