Bayesian ranking

Question

I have the following table in my database:

╔════════╦═════════════╦═══════════════╗
║  Name  ║ total_stars ║ total_reviews ║
╠════════╬═════════════╬═══════════════╣
║ Item A ║          27 ║             7 ║
║ Item B ║          36 ║             9 ║
║ Item C ║          27 ║             7 ║
║ Item D ║          30 ║             6 ║
║ Item E ║           0 ║             0 ║
║ Item F ║           0 ║             0 ║
║ Item F ║          15 ║             3 ║
╚════════╩═════════════╩═══════════════╝

I was looking at this article and trying to implement Bayesian rankings in PostgreSQL database.

The formula given for the rank is

br = ( (avg_num_votes * avg_rating) + (this_num_votes * this_rating) ) / 
(avg_num_votes + this_num_votes)

where:

• avg_num_votes: The average number of votes of all items that have num_votes>0
• avg_rating: The average rating of each item (again, of those that have num_votes>0)
• this_num_votes: number of votes for this item
• this_rating: the rating of this item

This is the query I came up with, but it is not working:

with avg_num_votes as (
      select AVG(total_reviews) 
           from business 
           where total_reviews != 0), 
       avg_rating as (
          select AVG(total_stars/total_reviews) 
          from business 
          where total_reviews != 0)
select * from business 
  order by ((avg_num_votes * avg_rating) + (total_stars)) / (avg_num_votes + total_reviews);

I am getting:

ERROR:  column "avg_num_votes" does not exist