Wednesday, May 12, 2021

The Sandwich Index

Sales of coffee and sandwiches might provide a reasonable guide as to how fast people are returning to the office. Bloomberg certainly think so. They have invented the Pret Index to measure the rate that people are returning to the workplace in the UK. As the UK emerges from lock-down Bloomberg is interested in observing how many people stop working from home and return to the office. In order to measure this Bloomberg is analyzing sales data from the Pret a Manger chain of sandwich shops. 

The Pret Index uses a baseline of average sales in a Pret a Manger restaurant from March 8th - the week before schools reopened in England. It then looks at how much sales have grown (or fallen) since that date and how close they are returning to the sales recorded in January 2020, before the start of the pandemic in the UK. Each 0.1 point on the Pret Index equals a 1% progress towards the January 2020 total of sales.

In Pret Sandwich Sales Show Office Workers Staying Home Bloomberg has created a story map to show where Pret sales are increasing and where they have seen little movement. In general it appears that Pret sales are increasing in major retail areas where shops have re-opened. However as yet there appears to be only the smallest of rises in commercial districts, suggesting that workers are not returning to the office in great numbers. 

Across the UK sales seem to be strongest in Yorkshire, which Bloomberg says is based on strong growth in the shopping centers of Leeds and York. Scotland, which has stronger lock-down rules than England, has seen very little growth on the Pret Index. 

Going forward Bloomberg says that they will be updating the Pret Index every week. Unfortunately the Pret Index, will obviously suffer from unforeseen changes in people's behavior when returning to work. For example many people returning to the office may avoid entering confined Pret a Manger's for their coffee and sandwiches. In the same way other measures may also prove problematic. For example analysis of public transit figures may prove a poor indicator of the numbers returning to the workplace if many commuters avoid packed trains and buses and find alternative means of transport.

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