Complex sentence: However, if interest rates fell then the regret associated with this choice would be large: -11 as the difference between the 1 received and the 12 which could have been received if the outturn had been known in advance.
Split into simpler sentences: However, if interest rates fell then the regret associated with this choice would be large. This would be -11, which is the difference between the 1 received and the 12 which could have been received if the outturn had been known in advance.