[OpenTRV-interest] Fwd: Count crowds with Bluetooth Connectivity Kit

Tue Dec 29 20:27:03 GMT 2015

Having had a small discussion about this, I'm even more dubious. 
There are systems that determine average speed and user counts for roads, using the Bluetooth ID, & obviously for speed it works - you can be fairly sure the ID is unique for a part of a road, you can discount speeds above 200mph and those IDs that vanish along the route, & get a good idea that what you get is the truth.
Counting cars is less certain - some (most  new) cars have a built-in BT device(s), others have none, & the occupants will have either no BT devices, BTs that are off, & BTs that are on. However, you can get an estimate using averaging. 
Counting people in cars, you have to average the car capacity from other studies, assuming they are correct for that road, then multiply by the already averaged count of vehicles from your BT loggers. 
Counting people though? Bad idea - without any other way to check it, it's going to basically be a random number. Imagine a house, essentially there are zero people with BT in each one unless they turn it on. You have no useful data. Most people switch BT on and off as they go to save battery, or just don't use it, & so it is always off. Others have geofence type software that turns it on when it is likely to be needed. Even if they have a (active) BT device it isn't them - it's a phone on a charger in another room, etc.
Some homes will have a dozen devices, always on. Most will have none. People? I'm pretty certain is going to vary hugely with the demographic. 
However. Nearly everyone has a cellphone. People turn off BT and wifi, but rarely do they turn off the actual phone part. An IMSI catcher would be a far better way of grabbing the crowd numbers. In fact it is so good that there are huge privacy implications! (Each cellphone can be tied to the number, & each one of those can be linked back to a database of the subscribers, complete with addresses - unlike BT where the number isn't anything really useful without a load of additional work. [That such complex and time consuming work can be easily automated using other databases & computers and even without it traffic analysis can tell you massive amounts, is for another day])
So no: you can't get even a rough guess on crowd numbers with Bluetooth without loads of extra data. 
Nigel
Sent from mobile

-------- Original message --------
From: Damon Hart-Davis <damon at opentrv.uk> 
Date: 29/12/2015  13:23  (GMT+00:00) 
To: "Open, non-developer list for interested parties" <opentrv-interest at lists.opentrv.org.uk> 
Cc: Damon Hart-Davis <damon at opentrv.uk> 
Subject: [OpenTRV-interest] Fwd: Count crowds with Bluetooth Connectivity Kit 

So, these people think you *can* count Bluetooth devices to estimate numbers of people around...

Begin forwarded message:
From: Cooking Hacks 
Subject: Count crowds with Bluetooth Connectivity Kit
Date: 29 December 2015 at 12:51:16 GMT

    Count crowds with Bluetooth Connectivity Kit

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                                             Count crowds with Bluetooth Connectivity Kit 

                                             If you cannot read this email properly, please click here

									Counting Bluetooth devices on New Year's Eve

										Every New Year's Eve, all around the world, millions of people get together to celebrate the last minutes in a crowded square. Times Square in New York, Puerta del Sol in Madrid, Trafalgar Square in London, Piazza dil Popolo in Rome, Champs Elysees in Paris or around Sidney Opera House. 

										Previous years, in Madrid, there were up to seven persons per square meter. Authorities have restricted the access to Puerta del Sol to prevent problems with crowd movements. Bluetooth Connectivity Kit can help to count bluetooth devices to estimate the amount of people that are celebrating the end of the year around you. 

                                                                        Read more

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