I am expecting to see a pattern in Discover with high impact but it isn’t returned – why is that?

There are two potential reasons:

1. The most likely reason is that Ipiphany has found the pattern you are expecting and determined that it is redundant. i.e. it is covered by another retained pattern. When analysing the patterns Ipiphany performs a number of tests for pattern overlap, equivalence and interest - and discards patterns that it determines as redundant. For example a pattern for Keyword= ‘loan’ may be discarded because a broader/stronger overlapping pattern for Theme=investment or Concept=Investment.
2. A pattern may also be discarded if it is determined that it’s not statistically significant