Effective rates are calculated on a phase-by-phase basis. Then the phase's revenues and profits are allocated to time slips on a weighted scale. Each hour worked by a highly compensated staffer is worth more than an hour worked by a lower-paid individual.
For hourly work, the hourly billing rates are used to weight their earnings. Fixed Fee phase use pay rates.
An example of a fixed fee phase
Staff A is paid $20 per hour and spends 18 hours on the phase, resulting in a labor cost of $360.
Staff B is paid $50 per hour and spends 5 hours, resulting in a labor cost of $250.
How much of the $2,000 in revenue from the phase is each person credited with earning?
$2000 (earnings) / $610 (labor) = 3.279 so...
Staff A earned $360 * 3.279 = $1,180.44 or $68.58 per hour
Staff B earned $250 * 3.279 = $819.75 or $163.95 per hour
Reality
At the end of the day, it is impossible to say whose effort actually contributed how much to the earnings. This is not an exact science. Perhaps Staff A is underpaid for the work they are doing. This would reduce their contribution and move funds to Staff B. Keep this in mind when looking at effective rates and earnings.