Measurements and data preparation
Define variables and resolve missingness
Measurement and recall windows should correspond to the question. Validate outcome definitions and examine whether exposure and outcome measurements can establish temporal ordering; often they cannot.
Flow diagram
Steps
Specify assessment period
Define simultaneous measurement timing and recall windows.
Define exposures and outcomes
Specify validated instruments, definitions and comparability.
Collect and check measurements
Review range, consistency and provenance.
Assess missingness and nonresponse
Prespecify item missingness and nonresponse adjustment.
Derive analysis dataset
Retain weights, strata, clusters and versioned derivations.
Measurements and data preparation
End flow
Tables and supporting information
Measurement dictionary
Document measurement definitions.
Missingness plan
Distinguish unit and item nonresponse.