Exhibit 2. Summary of Study Designs and Approaches Identified in Literature Review.

Studies	Totala
All	55
Design*
Pooled	22
Repeated Cross-sectional	17
Longitudinal/Panel	17
Use of Weights*
Unweighted	4
Cross-sectional weights	10
Longitudinal weights	4
Averaged or normalized weights	10
Not described/unclear	35
Approach for Survey Design Effects*
Used survey data software	33
Used other method (e.g., bootstrapping with PSUs)	3
Explicitly did not adjust for survey design	2
Not described/unclear	22
Approach for Repeat Observations*
Used longitudinal/panel data estimators	22
Used other methods (e.g., removed duplicate observations)	25
Explicitly treated observations as independent	2
Did not conduct statistics over time	4
Not described/unclear	15

^*Total exceeds 100% due to studies using multiple designs and approaches

SOURCE: Data collected by author