Hello! We’re interested in using SafeGraph’s cell phone data to track migration during the pandemic. Specifically, we are wondering if we can identify destinations in North Carolina and origins of cell used resettling in those destinations, and if we can look at the trend over the past year. I’m new to the SafeGraph data and I guess Social Distancing Metrics dataset is probably the one we should look into. But I still not fully understand the column descriptions after reading the documentation, especially the field destination_cbgs. Does anyone have any insights?
Hi @Huan_Lian_University_of_North_Carolina_at_Chapel_Hill, 1st I am sorry for the delay and second, sure - the social distancing file is broken up by the origin CBG, thus anyone who ‘lives’ in that CBG and goes elsewhere gets logged – in the documentation it states that the destination cbg captures that movement - i.e. how many people traveled to other destinations and which CBGs they were. If you check the schema you can see examples of the data to see what I mean-- please dont hesitate to ask for clarification on anything if it wasn’t clear
yes and no. it is 1 visits, but that that needs to be scaled up because SafeGraph does not capture/monitor all visits Simple Example of Implementing a “Micro” CBG-based Normalization Approach to estimate “True Visits” by day - Google Docs
I don’t know if you can distinguish people who migrate to another CBG vs just daytripping or vacationing.
Hi @Dennis_Chao_Institute_for_Disease_Modeling, thanks for your comment! I see in the documentation that “We determine the common nighttime location of each mobile device over a 6 week period to a Geohash-7 granularity (~153m x ~153m). For ease of reference, we call this common nighttime location, the device’s “home”.” I still not fully understand the methodology but I guess we can at least exclude the daytripping people?
The “home” is used as an origin for the devices. If you look at devices with a “home” in, for example, California, you might see that some were in Chapel Hill on a given day. You will not be able to tell how many of these devices moved from California to Chapel Hill vs visited Chapel Hill. If a device from California spends enough nights in Chapel Hill, that device’s home will be reassigned to NC, but you don’t know how many devices are reassigned from one CBG to another.