What is the test for a plaintiff to bring a claim for professional negligence?

In order to establish a claim for professional negligence, a plaintiff must demonstrate: 1) the duty of the professional to use such skill, prudence and diligence as other members of his profession commonly possess and exercise; 2) a breach of that duty; 3) a proximate causal connection between the negligent conduct and the resulting injury; and 4) actual loss or damage resulting from the professional's negligence. Jackson v. Johnson, 5 Cal.App.4th 1350, 1355, 7 Cal.Rptr.2d 482 (1992).