Count of travellers (origin-destination matrix, all pairs), per pair of localities per time interval
This is the number of ‘directional connections’ between each pair of localities, for each time interval. This is defined for each pair of localities as the number of unique subscribers that have visited the first locality within a time interval, and visited the second locality later in the same time interval.
You can find the SQL code for producing this aggregate in od_matrix_directed_all_pairs.sql.
The query od_matrix_directed_all_pairs_per_day is a standalone query which can be run by itself to produce the aggregate.
The first time you run this, you will need to include a timespan of data that includes the period before any mobility restrictions were enforced in your country, or before the first cases of COVID-19 were reported in your country. This is so that you can establish what ‘normal’ baseline behaviour looks like, and then see how this behaviour changed. We recommend that you include at least two weeks of ‘normal’ baseline data (i.e. the two weeks immediately before the announcement of restrictions or the outbreak), and preferably four weeks.
Once you have this baseline data, you can then run the query once every day, only looking at a single day’s data (yesterday).
We recommend that you calculate this aggregate for all available geographic divisions (e.g. state, municipality, district), and also modify the od_matrix_directed_all_pairs_per_day query to count connections per hour (see Note on calculating aggregates over multiple time intervals and locality sizes).
This aggregate is a simple measure of how much travel is occurring between each pair of localities. This is similar to Count of travellers (connections triangular matrix), but accounts for the direction of travel. For example, the count for locality_from=A and locality_to=B is the number of unique subscribers seen in locality A before locality B within the time interval.