The inclusion of variables for R&D cooperation in the model indicates that R&D cooperation is only of relatively minor importance as a medium for knowledge spillover.
Likelihood ratio tests determined appropriate inclusion of variables in the multivariate logistic regression model.
Identification is achieved by the inclusion of variables in Eqn. (2) that are excluded from Eqn. (1).
The results show that an inclusion of variables which are of little explanatory value to the model increase uncertainty.
Our criteria for inclusion of variables into the model included a p value <0.15 on univariate analysis, in accordance with published statistical methods [13].
The inclusion of variables at the district level does not produce any significant effect, and controlling for district fixed effects produces only small changes in the described results.
The inclusion of variables in the model was guided by the elements contained in the conceptual framework and grouping criteria were guided by frequency distribution.
A case in point is the inclusion of variables such as occupation, tenure, or job status that are usually considered 'endogenous' in the context of Mincerian wage OLS models but which are useful in the specification of the propensity scores model.
Multivariate analyses were performed by logistic regression, with inclusion of variables with p≤0.05, and analysis by Hosmer and Lemeshow Test.
Discriminant analyses were carried out with step-wise inclusion of variables (inclusion criterion of p≤0.05, exclusion criterion of p≥0.10), priors set to equal, and calculation of Wilk's lambda.
Inclusion of variables representing presence of allergen-specific IgE antibodies or of log10IgE in the multiple logistic regression model for asthma also had no major impact on our primary finding of an inverse association with CagA+ H. pylori strains.
