I was once an analyst for an aircraft component supplier. The Division Vice-President asked me for an estimate of the market size and of our sales for the next year. I had access to the best data in the whole world. My data listed every commercial airliner in the world (over 40,000 of them), by model and type, by owner, by tailnumber. It included hours flown for each aircraft, by month. I could tie this data to our records for each customer and tail number. I built a huge spreadsheet model and pasted the spreadsheets all over my office wall. Continue reading The Danger of False Concreteness →