Potential disaster as supermarket throughput falls

Michael Dilger
Last Updated 2020 Apr 4th

This is the content of an email I sent to MP David Seymour on March 26


I just want to make you aware of a potential disaster in the making of the "nine meals from anarchy" kind.

I have a MS in Computer Science and studied queuing theory among other things. Queuing theory is not my specialty, but I know enough to know that how supermarkets are being operated during this COVID-19 shut down is not going to work for more than a few weeks.

Right now people are well stocked and supermarkets are consequently nearly empty of shoppers. This is temporary. It's easy to stock up for one or two days, and everybody has done at least that. If people stocked up for four weeks, and we only have a four week shutdown, then everything will be fine. But if people didn't stock up, and if the shutdown goes longer, then this issue I'm raising will raise it's ugly head and become very obvious.


People need to eat. They need to eat the same amount they always ate. Normal throughput needs to be maintained for that to happen.

But we have extenuating circumstances. People can no longer get take outs or restaurant food, so they need to get all of their food from supermarkets. That means supermarket throughput needs to go UP.

Furthermore butchers, bakers, and vegetable shops have been ordered to close. That drives even more people into supermarkets again meaning their throughput needs to go UP.


Supermarkets and dairies are being operated in ways to promote social distancing. That spreads people out. But if there are less people in the store at any one time, that makes throughput go DOWN.

The reason it causes throughput to go down is because of Little's Law. Look it up.

Stores have also announced they are cutting back staff and cutting back hours. That makes throughput go DOWN. Think about it like this: same number of people, packed into fewer shopping hours.


The tell for this problem will be obvious: long lines of shoppers waiting outside of supermarkets for their turn to go shopping.


I hope I'm wrong. I hope people stockpiled for four weeks (I certainly did). And I hope the shutdown is over in four weeks. If that's the case, nobody needs to shop at all during this time. But if people shopped normally as they were told, and/or if the lock-down needs to extend longer, current policies will eventually prove disastrous.

Feel free to double check my thinking against any one else who has studied computer science queuing theory, or any other discipline that can credibly override this reasoning.

God help us all,

Ordering food online and having it shipped to your house is a mitigating factor of this condition. It might save us. You can help by doing all your shopping online.

And when butchers, bakers, and green grocers are again allowed to open, please give them your custom.