Filter out stories with low confidence

[johnwarden]

Problem:

• Many stories on the front page have only a few upvotes, and then stop receiving attention on HN.
• Our system decides these have a high true upvote rate, and so they maintain a high rank on QN until time penalty kicks in.
• The problem:
  • is we are not highly confident that these stories have a high quality because we have little data
  • these stories haven't gotten attention from moderators, so there is a good chance they are off topic.

Proposed Solution:

• Don't allow stories to rank on QN unless they meet certain threshholds, such as:
  • Making the HN front page
  • Some minimum number of upvotes.

Other idea: Have a separate page for "most underranked stories" that includes stories we filtered out in this way.