Empirical means statistically verifiable verifiable by observation not just an theory. I dont what part of that is hard for you to understand. The stats dont lie.
Heres another: Average house price in AB: 495,000. Average house price in ON: 852,000. Not hard to see why people are moving.
There isn't really a petro boom this time either. Oil and gas is doing fine but its not going crazy and booming like it was 20 years ago. We actually have fairly high unemployment of 7% considering the mass influx, but thats not stopping people from coming here. They're coming because ON and BC are completely unaffordable now and AB has some great advantages not the least of which is no provincial sales tax.