Of Mice and Ecomomics and medical decision making: "'No proposition in economics is more firmly established in economics than the supreme irrelevance of sunk costs.'"
This is especially true for infertile couples who are paralysed into inactivity when past treatments have failed. Because they have invested so much time, money and energy in their current doctor, they are very reluctant to consider switching. This can be a major mistake - and since getting a second opinion from an expert has become so easy, I just cannot understand why more patients don't do this routinely. It's important to start with a clean slate - and move on !