The GAF is intended to be a self-explanatory instrument and raters are almost never trained in its use.
In columns (1) and (3) the instrumented explanatory variable is enrollment rate; in columns (2) and (4) the instrumented explanatory variable is female enrollment rate.
In columns (1) and (3) the instrumented explanatory variable is average years of schooling; in columns (2) and (4) the instrumented explanatory variable is average years of schooling of females.
Given that the limited time duration of the analysis does not allow instrumenting explanatory variables, we deal with the possible presence of endogeneity by including the main macroeconomic variables discussed above in lag or with their annual change.
Alternative model specification was based on three criteria: validity of the instruments used; explanatory power of the instruments in the first-stage regression; and AIC (Akaike Information Criteria) in the second-stage (censored) regression.
33 37 Instrument: An explanatory model interview based on the EMIC framework will be adapted from the instruments used in the studies of oral cholera vaccine in Zanzibar, Kenya and DRC, based on the illness-related, vaccine-specific and setting-specific features of the study.
In light of the short time series dimension of the dataset, explanatory variables are not instrumented, and possible endogeneity issues (likely to be present especially for the unemployment variable) are addressed by taking lagged values of the explanatory variables.
The other measure uses the system-generalized method of moments (System-GMM), using the second lag of explanatory variables as an instrument to adjust the models (discussion of this method can be obtained from Blundell and Bond 1998; Roodman 2009).
To eliminate the specific effects of countries, we instrumented the explanatory variables of the equation in first difference by their values at the delayed level of a period or more (Chirinko and Singha 2000) (Table 3).
Each therapist received an explanatory cover letter, survey instrument, a notice of Research Information for the Participants from the University of Georgia's Institutional Review Board, an incentive to participate, and a postage-paid return envelope.
