#193

Hi Leon,

For this question, I got my query like this: 

WITH controlgroup AS
(SELECT COUNT(CASE WHEN reply_tweet_id IS NOT NULL THEN tweet_id END) as replies, 
       COUNT(DISTINCT CASE WHEN reply_tweet_id IS NULL THEN tweet_id END) as original_tweets
FROM tweets 
JOIN twitter_experiment_users
ON tweets.user_id = twitter_experiment_users.user_id
WHERE is_treatment IS FALSE AND exp_id = 2001)

,treatmentgroup AS
(SELECT COUNT(CASE WHEN reply_tweet_id IS NOT NULL THEN tweet_id END) as replies, 
       COUNT(DISTINCT CASE WHEN reply_tweet_id IS NULL THEN tweet_id END) as original_tweets
FROM tweets 
JOIN twitter_experiment_users
ON tweets.user_id = twitter_experiment_users.user_id
WHERE is_treatment IS TRUE AND exp_id = 2001)

SELECT treatment_replies - control_replies as diff
FROM
(SELECT controlgroup.replies * 1.0/controlgroup.original_tweets as control_replies, 
        treatmentgroup.replies * 1.0/treatmentgroup.original_tweets as treatment_replies
FROM controlgroup,treatmentgroup
) sub

I felt like the "replies" part might be the cause of my fault. Can you shed some light on this part?

Best

Ming