Every idea I was sure about, put in front of a  measurement 

A reconciliation check I had written mostly as a formality flagged Procter & Gamble's 2015 fiscal year. The four quarters I had reconstructed from their filings summed to $10,952 million of operating income. The annual figure P&G had filed for that same year was about 7% higher. Seven percent is far too large to be rounding, and far too clean to be random noise. It looked exactly like a parsing bug. I spent an afternoon convinced I had one. I did not. The quarters were right,

Most of what looked like a retrieval problem was really a document problem, and it had to be solved before retrieval could mean anything.