The Whole Person Impairment (WPI) approach was first indicated in the second reading speech that introduced the bill that brought about the SRCA and subsequently the Approved Guide in 1988. The Glossary in the Approved Guide includes the following discussion of WPI:

Whole Person Impairment means the medical effects of an injury or a disease and is drawn from the American Medical Association Guides where it is there referred to as 'whole man' impairment. Evaluation of whole person impairment is a medical appraisal of the nature and extent of the effect of an injury or disease on a person's functional capacity and on the activities of daily living. The Guides are structured by assembling detailed descriptions of impairments into groups according to body system and expressing the extent of each impairment as a percentage value of the functional capacity of a normal healthy person. Thus, a percentage value can be assigned to an employee's impairment by reference to the relevant description in this Guide.

The Principles of Assessment in the Approved Guide include another relevant discussion of the concept of WPI:

The Impairment Tables

Part 2, Division 1 of the Guide is based on the concept of 'whole person impairment' which is drawn from the American Medical Association's Guides.

Evaluation of a whole person impairment is a medical appraisal of the nature and extent of the effect of an injury or disease on a person's functional capacity and activities of daily living.

As with the American Medical Association's Guides, Part 2, Division 1 A of this guide is structured by assembling detailed descriptions of impairments into groups according to body system and expressing the extent of each impairment as a percentage value of the functional capacity of a normal healthy person.Thus a percentage value can be assigned to an employee's impairment by reference to the relevant description in this guide.