I'm not sure exactly what your data looks like or what amountOfClick and income are supposed to mean. One guess is that every time someone purchases something you send another row to your table with the value being the amount of money of that purchase. Perhaps you want to know
1. the average order amount which would be a "revenue" type metric
SELECT
user_id,
amount as value,
received_at as timestamp
FROM
purchase
as a SUM where the denominator is "orders per user"
2. the total revenue per user which would also be a "revenue" type metric
SELECT
user_id,
amount as value,
received_at as timestamp
FROM
purchase
as a SUM where the denominator is "All experiment users"
3. or perhaps just the orders per user which would be a "count" metric:
SELECT
user_id,
received_at as timestamp
1 as value
FROM
purchase
where the denominator is "All Experiment users"
All of which could be gotten from the same table. Does this answer your question?