A month ago, Google released a mobility report based on the anonymous aggregated data that were collected from the Location History of users’ smartphones all around the world.
These reports are meant to observe the movement trends in public places during the global lockdown due to the coronavirus pandemic.
By charting the movement of the public in areas like retail shops, parks, pharmacies, transit stations residential, and workplaces, it can be assessed whether the lockdown implementations are effective or not? And whether people are complying with these precautionary measures to prevent the spread of COVID-19 or not?
Google recently updated this mobility report for a large number of countries, and also covered major cities in those countries.
These Community Mobility Reports are only meant for charting the movement trends over time in various places. They are not at all intended to be used for medical or diagnostic purposes. They cannot be used for treatments of COVID-19 either. Also, this report cannot guide for travel plans.
Every Community Mobility Report only uses data from the Location and change in the number of visits to public places, where people can come in close proximity with each other and can cause the spread of the virus.
However, the Location accuracy can vary because it is totally up to individual users to either switch their Location in their phone settings on or keep it off. Users have full authority to delete their location history even. So, this report is only based on the majority data that could be collected, and it may or may not represent the exact percentage. But it gives an estimate, which is good enough to judge the situation and take the necessary steps to make amendments.
This is the reason why these reports should not be used to compare changes between various countries, or between rural and urban areas.
This also alleviates a major privacy concern, because all these reports are based on anonymized aggregated data, in which no personally identifiable information like names, contacts, or addresses are shared. Google is trying to take care of this issue rather strictly, so much so, that if a place does not have a lot of rush at a particular time, it does not notify the changes in that particular area at that time to maintain the anonymity of people that may be present. All this data is collected through similar anonymization technology that Google claims to use for all its services, like Maps.
Also, Google’s differential privacy allows adding artificial noise to their data, which helps in maintaining the anonymity of people and still present almost high-quality results.
In these reports, the changes of movement per day are compared to a median value, denoted as the baseline. All these data used for calculations only depend upon user settings, as mentioned above, and on Google’s privacy criteria. So, these reports can be assumed to be fairly safe and approximate.