Table 1.

Required research practices for research that used the National Inpatient Sample.

Domain	Research Practice No.	Required Research Practices For Conducting Research using the National Inpatient Sample
Data Interpretation	1	Identifying observations as hospitalization events rather than unique patients4,12
Research design	2	Not performing state-level analyses11
	3	Limiting hospital-level analyses to data from years 1988–201110,14
	4	Not performing physician-level analyses13,15
	5	Not using non-specific secondary diagnosis codes to infer in-hospital events16–20
Data analysis	6	Using survey-specific analysis methods that account for clustering, stratification and weighting6
	7	Accounting for data changes in trend analyses spanning major transition periods in the dataset (1997–1998 and 2011–2012)14,21