Putting DAGs to the Test: What Regression Reveals about Wildfire Drivers (Part 2)
This article puts the hypothesized causal DAG from Part 1 to the test by fitting
various Multiple Linear Regression models to ~4,000 large BC wildfires (>100 hectares) and
examining whether the atmospheric relationships we drew actually hold up in the data.
Before the main analysis, we take a pedagogical detour through Bayesian Multiple
Linear Regression using PyMC to demonstrate what happens when weakly informative
priors meet a large dataset and why that finding justifies switching to simpler
Frequentist methods for the rest of the analysis. The honest result: Our final model
explains roughly 11% of variance in fire size, which sounds underwhelming until you
consider what that 11% actually represents. Two of our hypothesized mediators don’t
survive contact with the data, and our revised DAG is far better for it.
