In the last days before the crash, the rush to build the railways added a final, lethal factor to the mix.

NEWYORKER: Boss Rail

Here's another, big factor to add to the mix - the facts around inward migration.

BBC: 2011: The Year of Sharp Decreases

With an understanding based only on correlation and not causality, we challenge mix modelers to rationally explain where their long-term factor comes from (whatever value it is) and by what mechanism or how it becomes actual, longer-term consumer purchases.

FORBES: The Downside Of Marketing Mix Models Is There's No Upside For CMOs