add description for summary

README.md

@@ -3,6 +3,9 @@
 > 💡 If you are teaching at the University of British Columbia, you may also be interested in the tool `Threadz` which provides visualizations and data from your Canvas discussion forums through a user interface in Canvas. You can learn more about the tool and how to request access in your course from the [LTHub Instructor Guide](https://lthub.ubc.ca/guides/threadz-instructor-guide/). `Threadz` was developed by Eastern Washington University.
 
 # Canvas Discussion
+
+### Data
+> `{course_id}-discussion.csv`
 This project pulls data via the Canvas API the discussions for the specified Canvas course(s) and exports the results as CSV. The columns exported are:
 * 'topic_id',
 * 'topic_title',
@@ -21,6 +24,25 @@ This project pulls data via the Canvas API the discussions for the specified Can
 
 Where a `topic` corresponds to a `discussion_topic` and `post` refers to replies to the `discussion_topic`. If a `discussion_topic` has no posts then you will see the `topic_` columns filled with no corresponding `post_` data. A `post` may have a `post_parent_id ` if it is part of a threaded response.
 
+### Summary Data
+> `{course_id}-discussion-summary.csv`
+
+We have calculated summary metrics for each topic. The csv with the summary information includes the following columns:
+* 'topic_id',
+* 'topic_title',
+* 'topic_author_id',
+* 'topic_author_name',
+* 'topic_created_at', 
+* 'topic_posted_at',
+* 'number_of_posts': the total number of posts and replies in the topic
+* 'median_posts_word_count': the median word count for all posts and replies to the topic
+* 'average_time_to_post_hours': the average time to post or reply from the topic created_at date
+* 'first_reply_timestamp': the timestamp of the first post
+* 'average_time_to_post_from_first_reply_hours': the averate time to post or reply from the first post (for cases where all discussions are released at once, this may be a more meaningful mettric of time to reply)
+* 'average_posts_per_author': the average posts per author (does not include enrollments with no posts)
+
+Where a `post` is a response to a topic, and a `reply` is a reply to the post. 
+
 ## Getting Started
 These instructions will get you a copy of the project up and running on your local machine for use with your own API tokens and Canvas domains.