What is the test for placing a plaintiff in a different position than their original position?

Athey v. Leonati recognizes that the “essential purpose and most basic principle of tort law is that the plaintiff must be placed in a position he or she would have been in absent the defendant’s accident (the ‘original position’)”. The following is stated at paragraph 32 in the Athey case: However, the plaintiff is not to be placed in a position better than his or her original one. It is therefore necessary not only to determine the plaintiff’s position after the tort but also to assess what the “original position” would have been. It is the difference between these positions, the “original position” and the “injured position”, which is the plaintiff’s loss.