What is the test for assessing pre-trial loss of income for a plaintiff who is injured in a motor vehicle accident?

Similarly, in Wittmeier v. Scholes 1999 ABQB 4 (CanLII), [1999] A.J. No. 12 (Q.B.), the trial judge heard expert evidence on pre-trial loss of earning capacity for a dentist who had been injured in a motor vehicle accident. The award for pre-trial loss of income that the trial judge ultimately made was based on averages and projections provided by the expert witness. There does not appear to be a strict requirement for proof of actual loss when determining pre-trial loss of income and there is nothing wrong with assessing the damages in much the same way as damages for future loss of income are calculated.