What are the principles governing the assessment of damages for loss of earning capacity?

I now turn to the claim for damages. The principles guiding the assessment of damages for personal injuries, particularly for loss of earning capacity, were succinctly summarized by Madam Justice Huddart in Rosvold v. Dunlop, 2001 BCCA 1, 84 B.C.L.R. (3d) 158, at ¶8 to 11: The most basic of those principles is that a plaintiff is entitled to be put into the position he would have been in but for the accident so far as money can do that. An award for loss of earning capacity is based on the recognition that a plaintiff's capacity to earn income is an asset which has been taken away. Where a plaintiff's permanent injury limits him in his capacity to perform certain activities and consequently impairs his income earning capacity, he is entitled to compensation. What is being compensated is not lost projected future earnings but the loss or impairment of earning capacity as a capital asset. In some cases, projections from past earnings may be a useful factor to consider in valuing the loss but past earnings are not the only factor to consider. Because damage awards are made as lump sums, an award for loss of future earning capacity must deal to some extent with the unknowable. The standard of proof to be applied when evaluating hypothetical events that may affect an award is simple probability, not the balance of probabilities. Possibilities and probabilities, chances, opportunities, and risks must all be considered, so long as they are a real and substantial possibility and not mere speculation. These possibilities are to be given weight according to the percentage chance they would have happened or will happen. The trial judge's task is to assess the loss on a judgmental basis, taking into consideration all the relevant factors arising from the evidence … [The factors] include: