That's essentially a statistics / data analytics question. Statisticians (et. al) are well versed at receiving a whole bunch of messy data and figuring out the

That's essentially a statistics / data analytics question. Statisticians (et. al) are well versed at receiving a whole bunch of messy data and figuring out the value that they want to observe. From a rough perspective, I think it would look something like this: 1) There will be a large concentration of people reporting pressures that are on the low side, this is the true outside pressure. 2) There will be clusters of people reporting high pressures, and that will be inside buildings. 3) To ignore funny circumstances where large amounts of people are reporting lower pressures than the true outside pressure (I'm not sure why this might be, but this is not my domain of expertise) you can compare it to the pressure that people are seeing around that area, and to official pressure readings.