Enabling analysts to produce mobility indicators from CDR aggregates
This section lists and describes, split by indicator categories, the mobility indicators that analysts can produce utilising MNOs' CDR aggregates.
For each indicator, we also list the aggregates required to produce this indicator.
Subscriber presence
Indicators based on time series of Count_subscribers aggregates
Subscriber presence - Hourly/daily presence (weekday), per region
Number of subscribers recorded in each region each hour/day, during weekdays: this describes how busy each region is during weekdays, and during each hour of weekdays
Unit
% change relative to baseline
CDR aggregate(s) required
Count_subscribers (hour, local)
Count_subscribers (day, local)
Count_active_residents
Count_events
Subscriber presence - Hourly/daily presence (weekend), per region
Number of subscribers recorded in each region each hour/day, during weekends: this describes how busy each region is during weekends, and during each hour of weekends.
Unit
% change relative to baseline
CDR aggregate(s) required
Count_subscribers (hour, local)
Count_subscribers (day, local)
Count_active_residents
Count_events
Subscriber presence - Changes to variance of hourly/daily presence, per region
The variance in hourly/daily patterns, across different days/weeks: this provides information about the extent to which previously predictable, regular patterns have been disrupted.
Disruption duration: A further indicator may be the time it takes for presence patterns to become regular again.
Unit
% change relative to baseline
CDR aggregate(s) required
Count_subscribers (hour, local)
Count_subscribers (day, local)
Count_events
Subscriber presence - changes to day/night subscriber presence ratio, per region
Ratio of the number of subscribers recorded in each region during ‘daytime’ hours, and the number during ‘nighttime’ hours: this provides information about the number of residents (who are likely to be present during the nighttime) versus the number of non-residents (who are likely to be present during the daytime) that visit the region. It can also provide information about which regions are popular night-life spots (a high proportion of nighttime visitors).
Unit
% change relative to baseline
CDR aggregate(s) required
Count_subscribers (hour, local)
Count_subscribers (day, local)
Count_active_residents
Count_events
Home locations
Indicators based on time series of Count_residents and Count_home_relocations aggregates
Home locations - Changes to the number of resident subscribers per region
Number of subscribers that are assigned to a region as their home region.
Unit
% change relative to baseline
CDR aggregate(s) required
Count_residents
Home locations - changes to the number of subscribers who move home, per pairs of regions
Number of subscribers whose home location has changed, between any two regions or for specific regions.
Unit
% change relative to baseline
CDR aggregate(s) required
Count_home_relocations
Count_events
Home locations - duration of disruption, per region
Average time for a region to get back to its pre-crisis subscriber population size (if at all).
Unit
Weeks
CDR aggregate(s) required
Count_home_relocations
Count_events
Count_active_residents
Crowdedness measure
Indicators based on time series of Count_subscribers (15min, urban cluster)
Crowdedness measure - crowd size per cluster
Number of subscribers recorded at each cluster within a 15 minute interval (urban areas only): this measures the size of a ‘crowd’.
Unit
% of residents
CDR aggregate(s) required
Count_subscribers (15min, urban cluster)
Crowdedness measure - crowd frequency per cluster
Number of ‘crowds’ (defined to be more than X subscribers recorded at the same cluster within a 15 minute interval) recorded each day: this measures the frequency with which crowds congregate.
Unit
N per day
CDR aggregate(s) required
Count_subscribers (15min, urban cluster)
Population mixing
Indicators based on time series of Count_subscribers (day, local) and Count_subscribers (week, local) and Count_residents (local)
Population mixing - visitors vs residents, for each region
Number of unique subscribers recorded in the region each day/week, normalised by the number of subscribers that have that region assigned to them as their ‘home region’: this is an indicator of how many non-resident ‘outside’ visitors come to the region, relative to the size of the resident population.
Unit
% of residents
% change relative to baseline
CDR aggregate(s) required
Count_subscribers (day, local)
Count_residents
Count_active_residents
Population mixing - ‘mixing factor’, for each region
Average number of unique visitors each day, averaged over a week, divided by the number of unique subscribers to the region in a week: this indicates the degree to which the same people visit a region each day, versus different people visiting each day which would result in higher ‘mixing’.
Unit
% of unique week visitors
% change relative to baseline
CDR aggregate(s) required
Mean Count_subscribers (day, local) divided by Count_subscribers (week, local)
Intra-regional travel
Indicator based on time series of Count_subscribers (day, local) and Count_subscribers (day, regional)
Intra-regional travel - changes to travel within each region
Average number of sub-regions visited in each region per visitors to the region: this measures the amount of movement within a region.
Unit
% change relative to baseline
CDR aggregate(s) required
Mean Count_subscribers (day, local) divided by Count_subscribers (day, regional)
Inter-regional travel
Indicators based on time series of od_matrix_directed_all_pairs, od_matrix_directed_consecutive_pairs and Count_visits_home_away.
Inter-regional travel - changes to incoming flow to each region
Number of subscribers entering a region from another region.
Unit
% change relative to baseline
CDR aggregate(s) required
od_matrix_directed_consecutive_pairs
Count_events
Inter-regional travel - changes to outgoing flow from each region
Number of subscribers leaving a region and travelling to another region.
Unit
% change relative to baseline
CDR aggregate(s) required
od_matrix_directed_consecutive_pairs
Count_events
Inter-regional travel - changes to net flow of each region
The difference between incoming and outgoing flows: this measures how subscribers are redistributing amongst regions.
Unit
% change relative to baseline
CDR aggregate(s) required
od_matrix_directed_consecutive_pairs
Count_events
Inter-regional travel - changes to the distribution of distances travelled
The median distance (and quartiles) travelled by all subscribers that travel to the region from another region: this indicates whether a lot of people come to the region from nearby regions, or from regions that are farther away.
Can be aggregated across regions.
Unit
% change relative to baseline
km
CDR aggregate(s) required
od_matrix_directed_all_pairs
Inter-regional travel - changes to the dispersion distribution
For each destination region, this is the average percentage of subscribers that originated from each region: this indicates whether a lot of people originate from the same region, or whether there are many origin regions with a few people coming from each one.
Variant: standard deviation of coordinates of origin regions.
Unit
% change relative to baseline
km
CDR aggregate(s) required
od_matrix_directed_all_pairs
Inter-regional travel - changes to the mixing factor
Average ‘mixing factor’ of origin regions: indicates whether visitors are coming from a ‘high-risk’ (or ‘high-contribution’) region.
Unit
% change relative to baseline
CDR aggregate(s) required
od_matrix_directed_all_pairs
Inter-regional travel - changes to the number of regions visited, per home location
Average number of regions visited by the resident subscribers of each region.
Variant
Exposure (or contribution): changes to the number of hotspots visited, per home location
Average number of hotspots visited by the resident subscribers of each region)
Unit
% change relative to baseline
CDR aggregate(s) required
Count_visits_home_away
Inter-regional travel - changes to the line distance travelled, per home location
Average distance to visited regions by the resident subscribers of each region.
Unit
% change relative to baseline
km
CDR aggregate(s) required
Count_visits_home_away
Inter-regional travel - changes to the dispersion of visited regions per home location
Standard deviation of coordinates of visited regions by the resident subscribers of each region.
Unit
% change relative to baseline
km
CDR aggregate(s) required
Count_visits_home_away
Inter-regional travel - changes to the number of subscribers visiting a single region, per region
More specific indicator on the number of subscribers not crossing admin boundaries.
Unit
% change relative to baseline
CDR aggregate(s) required
Count_subscribers_single_region
Inter-regional travel - changes to the number of subscribers visiting only their home region, per home region
More specific indicator on the number of subscribers not recorded outside of their home region.
Unit
% change relative to baseline
km
CDR aggregate(s) required
Count_subscribers_home_region
Locations of interest
Locations selected from the analysis of population mixing indicators and the analysis of the graph formed by the inter-regional travel aggregate od_matrix_directed_all_pairs.
Regional connectivity structure: isolated clusters of regions
Are there areas of the country isolated for the rest? (which may be easier to protect).
Unit
Names
Coordinates
CDR aggregate(s) required
od_matrix_directed_all_pairs
Regional connectivity structure: main travel routes
List of locations most connected to each other forming a path through the country (along which the virus may spread).
Unit
Names
Coordinates
CDR aggregate(s) required
od_matrix_directed_all_pairs
Regional connectivity structure: main travel routes through hotspots
Path along which most population mixing is occuring (along which the virus may spread).
Unit
Names
Coordinates
CDR aggregate(s) required
od_matrix_directed_all_pairs
Hotspots: locations of hotspots
Locations with high population mixing values and/or crowdedness.
Unit
Coordinates
Indicators required
Population mixing indicators
Crowdedness indicators
Other type of indicators
Sample size / Data quality indicators
Sample size / Data quality indicators
These are not indicators of mobility but serve to control for changes in the CDRs that may lead to a misinterpretation of mobility indicators, and to assess uncertainty from the variations of the sample size (number of events and subscribers used to compute the indicators).
Sample size/data quality indicators - number of events
The total number of calls/SMS/data sessions in each region each hour/day.
This is to provide an indicator of the sample (data) size that we are working with in order to know if the analysis for particular regions and times should be discounted due to insufficient data. It also enables to check whether an increase in ‘subscriber counts’ may actually just be due to the normal number of subscribers using their phone more, and to easily determine if there is an issue with e.g. missing data one day.
Unit
N per region per time interval
CDR aggregate(s) required
Count_events
Sample size/data quality indicators - ‘residents’ activity level
The proportion of residents in a region who use their phone each hour/day, divided by the total number of residents (where ‘residency’ is defined via a home region): this indicates how active the subscribers in each region are.
Unit
% of residents
CDR aggregate(s) required
Count_residents
Count_active_residents
Sample size/data quality indicators - new subscribers
Percentage of all subscribers who are ‘new’ (appeared in the dataset for the first time within the last week): this provides information about how much data we have for subscribers (to inform statistical validity of analyses).
Unit
% of subscribers
CDR aggregate(s) required
Count_residents