Definitions

CompletedA completed event occurs when a visitor reaches the last prompt in a conversation or when a visitor exhausts all the content in a conversation.
One completed event per visitor, per session.
People AcquiredHappens when a visitor submits their email address.
One acquisition per visitor, per session.
Engagement RateNumber of users responded (first input by user)/number of triggers (chatbot displayed).
Conversion RateUser acquired (new emails captured)/user engaged.

Marketo Engage