HDSS Migration Data

The indicators available are Crude in-migration rate (CIMR), Crude out-migration rate (COMR), Age-specific in-migration rates (ASIMR), Age-specific out-migration rates (ASOMR), Crude net-migration rate (CNMR) and Crude gross-migration rate (CGMR).
 
Migration
Migration is defined as a change of residence. Minimum time to be considered a resident varies from one HDSS to the other but a standard of six months have been adopted for INDEPTHStats (see Population). In-migrants are residents after they have spent more than six months in the demographic surveillance area. Out-migrants are no longer residents after they have spent more than six months outside the demographic surveillance area.
 
Crude in-migration rate (CIMR)
CIMR is the number of in-migrations divided by the person-years of all ages, expressed in in-migrations per 1000 person-years. 
NB: CIMR depends on age-structure, which evolves from one calendar year to the next and from one HDSS to the other. Therefore CIMRs are not strictly comparable over the period and across HDSS. 
 
Crude out-migration rate (COMR)
COMR is the number of out-migrations divided by the person-years of all ages, expressed in out-migrations per 1000 person-years. 
NB: COMR depends on age-structure, which evolves from one calendar year to the next and from one HDSS to the other. Therefore COMRs are not strictly comparable over the period and across HDSS. 
 
Age-specific in-migration rates (ASIMR)
ASIMR is the number of in-migrations in a specific age-group divided by the person-years lived in that age-group, expressed in in-migrations per 1000 person-years. 
 
Age-specific out-migration rates (ASOMR)
ASOMR is the number of out-migrations in a specific age-group divided by the person-years lived in that age-group, expressed in out-migrations per 1000 person-years. 
 
Crude net-migration rate (CNMR)
CNMR is the number of in-migrations minus out-migrations divided by the person-years of all ages, expressed in net-migrations per 1000 person-years. CNMR may be positive or negative.
NB: CNMR depends on age-structure, which evolves from one calendar year to the next and from one HDSS to the other. Therefore CNMRs are not strictly comparable over the period and across HDSS. 
 
Crude gross-migration rate (CGMR)
CGMR is the number of in-migrations plus out-migrations divided by the person-years of all ages, expressed in migrations per 1000 person-years. 
NB: CGMR depends on age-structure, which evolves from one calendar year to the next and from one HDSS to the other. Therefore CGMRs are not strictly comparable over the period and across HDSS.