You can publish some correlations between prices. (Remember there is no known method where you can look at a time series of prices across stores and say “that’s collusion!”). And hey if you have 10,000 - 100,000 products per store you probably have correlations as high as you want. None of that will actually show collusion or more importantly suggest a policy response.
Even very high correlation _within a category_ across stores isn’t going to do that. Say you find price movements in tomato paste across all N chains are 0.95… ok now what? There are 10,000 or 2,000 product categories so you found a high correlation in one of them what do you want to do about it?
What I want to happen is for those people to realize that they're not alone, and that the whole world is not working to put them at a disadvantage. Really, it's a rather small group of people who are setting the rest of us up to be rats in a maze with no exit. Then I want us to find those people, and go after their bottom line. Nothing violent, just like... welding the doors shut on opening day, that sort of thing.
It might be less rational than something more restrained like getting a law degree and working in the system to bring them to actual justice. But it has... a glimmer of rationality. You're no longer an insane lone wolf lashing out against an impossible situation... now you're a shitty activist, and even if you're not acting with a cohort, you know that cohort is out there. You're not stuck, you're not alone, there's a path forward--you can aspire towards being a less shitty activist.
But it requires a justifiable target, a representative of the untenable situation. A list of potential enemies that's far less than everybody. Once that list exists, I want companies to compete to not appear on that list.
Markets work without being rational, as does evolution (some predation required). This would be the same.
What an unbelievably stupid thing to advocate for, much less under the guise of non violence.
That’s all this metric will show.
It also won’t show supply chain issues that make the Canadian grocery industry look the way it does. As an example, buy 100 head of cattle in western Canada and get the beef into a store. Are you having any luck finding a place to process it?