I have been practicing personal injury law in San Diego county California since 1999; and since that time, I have come to one conclusion about what the biggest value driver is in a given person's injury case in the state of California:  

The answer is a little complex:   apart from the "actual injuries" the person has suffered, the question becomes whether the injured person has a permanent impairment to a particular body part (or parts) from the accident, and, more importantly, is that impairment to a particular body part properly documented under the American Medical Association 5th Edition Guidelines by a duly licensed medical doctor in California?

Please keep in mind, the above answer means your biggest piece of evidence in terms of arguing case settlement value is,  besides your actual documented injuries that your doctors have documented for you, whether you have a medically documented impairment to a function of a body part or parts.  This is the big secret to the true value of any injury case for settlement or for a jury to consider in terms of damages, and it is often overlooked by the doctors, and the lawyers who practice in personal injury law in California.

Why is the AMA 5th Edition so important?   
Well, if it is warranted on your particular case, it can help your injury lawyer establish the following (
which basically boils down to value points, or value drivers, for your injury case):

1.  A medically supported impairment to a body part by a medical doctor;
2.  A medical expert that can be called as a witness at or before trial to support the permanent impairment;
3.  The degree or percentage of that impaired body part in relation to your entire body;
4.  Future medical care based on the impaired body part or parts;
5.  Duties under duress, and loss of enjoyment of life damages backed by a medical doctor;
6.  An objective finding supporting the impaired body part; the claims adjuster or jury get an opportunity to understand the permanency of your injury;
7.  Credible, independent, and objective evidence as to your impairment that is respected world-wide;

Also, did you know?
1.  It is used by the insurance company's reviewing your case for settlement value;
2.  The majority of the insurance companies, when reviewing an injury case, use a computer program that asks them whether or not there is an impairment to a particular body part, and if it is documented per the AMA guidelines by a medical doctor;

Here is some more information for you to consider:
In order to help get the message out to injured consumers in California, I put together some informational videos explaining the above secret (just click on the following videos):

Here is a Video I did on How Computers are used by the Insurance Companies to Get Your Settlement Value 

Here is a Video I did on How an Claims Adjuster puts in Data on Your Injuries into a Computer Program to come up with Settlement Value

Here is a Video I did on How California Zip Codes Can Affect the Value of your California Injury Case