What is the proper calculation for lost or diminished earning capacity?

The proper approach to determining lost or diminished earning capacity is set out in Rosvold v. Dunlop, 2001 BCCA 1, at para. 8 as follows: The most basic of these principles is that the 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 [citations omitted]. 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.

The plaintiff is required to establish an impairment of her earning capacity as a capital asset. Here, I cannot find on the evidence that the plaintiff is likely to be less capable of earning income in her settled career as a retail merchandiser because of her left wrist condition. She still works forty to fifty hours a week, depending on contracts. There is insufficient evidence here of a "substantial possibility of loss of income earning capacity" to support this claim. See Bedwell v. McGill, 2008 BCCA 6, at para. 53:

In addition, it was necessary for the appellant to have proven a substantial possibility of a future event leading to an income loss (see Steward v. Berezan, 2007 BCCA 150, 64 B.C.L.R. (4th) 152 at para. 17). Based on the trial judge's finding with respect to the extent of her ongoing injuries caused by the accident and the fall, and the lack of evidence that such injuries could lead to a future income loss, it follows that she did not prove such a substantial possibility.