# 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
