How to Examine External Validity Within an Experiment

Area of Science:

• Econometrics
• Experimental Design
• Policy Evaluation

Background:

• Experimental estimates may lack external validity for alternative policies.
• Assessing external validity often involves comparing experimental data with external datasets.
• A gap exists in methods for evaluating external validity within a single experiment's data.

Purpose of the Study:

• To introduce methods for assessing external validity internally within experimental data.
• To provide accessible approaches from the treatment effects literature.
• To facilitate the examination of generalizability for policy analysis.

Main Methods:

• Discussion of treatment effects methodologies.
• Application of stylized examples for clear illustration.
• Focus on internal assessment techniques for external validity.

Main Results:

• Researchers can utilize existing treatment effects frameworks to assess external validity.
• Internal examination provides a preliminary step before external data comparison.
• The presented approaches offer a structured way to begin validity checks.

Conclusions:

• Internal assessment of external validity is feasible using established econometric techniques.
• These methods enhance the understanding of an experiment's generalizability.
• The study provides practical tools for researchers designing and analyzing experiments.