Field Experiment

Is it possible to randomize exposure to the different levels of the predictor?

Is there natural variation in the predictor in the field?

Quasi-Experiment

Is the variation over time in the predictor exogenous?

Selected endogeneity threat

Sensitivity Approach

Run a sensitivity analysis (click for more information).
After running a sensitivity analysis: Is it (still) likely that an unobserved confound would alter the conclusion?

Is a strong and valid instrument for the predictor available?

Click here for more information on finding instruments.

Are instrument-free approach requirements fulfilled?

Click here for more information on the Instrument Free Approach.

Is it possible to triangulate the results with a controlled study?

Click here for more information on multi-method approaches.