As a general matter, you start with the most you could possibly get, if you sued and won, and then reduce it by around 40 - 60% since you almost always accept less in a settlement for various reasons:1) When you settle before trial, you save alot of money on legal expenses, so you can afford to take less;2) Settling before trial, you get the money months or often years earlier, and getting the money faster has a real economic value;3) If you settle, you are guaranteed to get paid--whereas if you go to trial, you could lose (even the best cases lose sometimes) or just get less than you hoped;4) The incentive for the other side to settle is that they will pay less than if they lose at trial--the opportunity to save money and pay less is what encourages them to settle.In terms then of figuring out the maximum you could get if you went to trial and won, add up:a) The *additional* medical expenses caused in this case by the failure to diagnose her correctly immediately. If she had a broken back, medical costs would been accrued even with a prompt and accurate diagnosis. What the misdiagosis may have done is increase those costs, by allowint extra damage to occur during those two days. Whatever those additional costs were--both paid to date and prospective future (and including prescriptions as well as therapy, in addition to surgery, tests, X-rays, etc.) could be recovered.b) Additional out-of-pocket costs for her (if she was an adult) or her legal guardians (e.g. you) if she is minor due to the delay--such as if you had to take more time off from work and lost income due to the misdiagnosis.c) "Pain and suffering" if the misdiagnosis and delay caused some additional long-lasting (weeks or more) impairment, disability, or loss of function than she would have had if she had been diagnosed properly immediately--such as if, for example, she will, due to the delay, have some restricted motion in her back, residual weakness, and/or some frequent or constant pain. A pain and suffering award is typically anywhere from 1/2 the medical costs to 2 - 3 times the medical costs, depending on severity, duration, etc.d) Lost future earning potential, if this (the misdiagnosis or delay) will restrict or disable her from work to some degree.Add up a) - d), then be prepared to settle for around half, give or take, of that number if you can settle ahead of trial.