If (let's say) only 10% of boot camp developers went on to get a development job, and that's roughly the 10% that still reads HN, then they're all going to answer "Yes, I feel that the bootcamp prepared me for the job I got." the other 90% of bootcamp students will answer no, but if they aren't here on HN they won't answer at all. That's selection bias and it's a huge problem for the exact questions the OP asked.