Let me start with few questions:
1. How're we doing it right now? --> Users have an option to 'Like' the post
2. Why did we launch 'Likes' in the first place? --> What do you feel?
Let me think about it. First off, let me segment the different users:
1. Heavy Posters --> These are the 1% of the users who are always active on Facebook. They're posting all the time, adding new friends, commenting, etc. They're are the content creator!
2. Frequent Posters --> These are the 9% of the users, who sometimes participate on daily FB's activities.
3. Occasional Posters/Lurkers --> These are the 90% of the user who usually lurks around
As a FB PM, I would have seen this pattern and wanted more participation/engagement from all user segments. --> Seems fair assumptions
Let me list the needs/pain-points of each segment:
1. Heavy/Frequent Posters --> When others don't engage on their posts, they lose motivation to produce content/posts and thereby they come less on FB, and FB loses its power of having an engaging community.
2. Lurkers --> They like the posts but don't want to comment, they want an easy way to show their appreciation.
Looking at the above problems, 'Likes' seems to be the solution. 10% of users posting and 90% 'Liking'
Now, extending the above analogy, I see we can have more emotions - “love”, “haha”, “wow”, “sad”, and “angry” catering to the distribution of the 90% of the users as not all 90% will have a need to 'Like', they have other emotions like “love”, “haha”, “wow”, “sad”, and “angry”
So, from the above hypothesis, I see # of posts having only 'Likes' will < #posts having 'reactions'
Other Success metrics will be:
1. # of posts with reactions / # posts without reactions
2. Reactions leading to more posts --> # reactions / # total posts --> Cohorts of posts before and after reactions can be measured
3. Reactions leading to more active users --> # unique users before and after reactions
4. Reactions leading to other activities --> 'Add Friends', 'Comments', and 'Chats'
To summarize, I feel reaction will increase overall engagement as we're targeting a larger distribution of user and their emotions, and an ability to portray these emotions will lead to an increase in engagement