A general concern with policy evaluation studies based on non-experimental designs is the possibility that such studies are flawed because the adoption of policies is often endogenous.
Nevertheless, estimates of causal effects based on non-experimental data may always be affected by unobserved confounders and therefore should be interpreted with caution.
In this regard we make use of propensity score matching, which allows for the estimation of causal effects based on non-experimental survey data (Guo and Fraser [2010]; Rosenbaum and Rubin [1983]).
Estimation of the differences in the welfare of farm households of the participants and non-participants based on non-experimental observation is not trivial because of the need to identify the counterfactual situation had they not participated in dairy hub.
Constructing a valid control group under these circumstances is challenging, and we relate our discussion to recent advances in econometric methods for evaluation studies based on non-experimental data.
Yet, irrespective of the fact that we control for a diverse set of potentially relevant characteristics, unobserved factors that are not related to the variables based on which we balance the sample always pose a potential risk when assessing causal effects based on non-experimental survey data.
Excluded were annotations based on non-experimental findings ('potential'probableble' or 'by similarity').
(To be clear, the test score impact estimates in Miguel and Kremer (2004) come from a regression analysis that relies on the experimental comparison between the treatment and control groups, and is not a retrospective analysis based on non-experimental data).
Instead of using existing empirical mathematical correlations based on non-standardized experimental setups to predict the mass transfer coefficient, methods to measure the mass transfer coefficients directly on a specific reactor set-up can be used.
Using a modified porous electrode theory based on non-equilibrium thermodynamics, we show that experimental phase behavior can be accurately predicted from free energy models, without artificially placing phase boundaries or fitting the open circuit voltage.
Indirect comparisons based on non-randomised trials.
