# Validity estimators For a general concept description see ../03-documentation/terms_of_reference-key_terms.md#validity From Maitrot2017 -> Section 4, Figure 3 and Appendix table notes They rank *only* quasi-experimental/experimental Do we too? ## internal 0-5 ranking using study design/method: OLS=2 (ordinary least squares) DID=3 (difference-in-difference)/(-in-difference) DM=3 () PSM=3.5 (propensity score matching) IV=4 (instrumental variable) RD=4.5 (regression discontinuity) RCT=5 ## external non-representative surveys=2 sub-nationally representative surveys=3 nationally representative surveys=4 surveys based on census data=5