However, once instrumented, migration experience is no more significant, except in columns (1) and (7).
To address this issue, we use an instrumental variable approach, and we instrument the migration prevalence with older migration rates, using the fact that departures tend to be more frequent in places where historic migration rates have been higher.
Precisely, if t = 2006, we instrument the migration prevalence for 1998 2005 departures using the local migration prevalence computed on pre-1998 departures 10.
In order to create an instrument for migration we need to classify immigrants according to their country of birth and consider where immigrants had historically settled.
The instrument for current migration is potential migration.
10 Similarly, for t = 1998, we instrument the 1990 1997 migration prevalence with the one based on pre-1990 departures.
To address this problem, an exogenous variable (Z) is employed as an instrument for the migration status in a two-stage least squares (2SLS) setup.
Mercury intrusion porosimetry was used to test the pore structure of the mortar in RAC, and the rapid chloride migration instrument was selected to investigate the diffusivity of RAC.
While the F statistic for the excluded instruments on the migration indicator was 7.8 (Table 2), the KP statistic (3.4) indicates that the instruments as a set are weak when we endogenize all four of these measures.
Columns 2 4: network variable is instrumented using old migration rates (based on 1990 1998 departures) in level and interaction terms.
IV: network variable is instrumented using old migration rates (based on pre-1998 departures when t=2006, pre-1990 when t=1998) in level and interaction terms.
