1: Queries in place to identify the following types of scenarios: For 9 of 10 study sites a mandatory and critical variable is only missing in 5% of the subjects. For site 10 data is found to be missing in 30% of the subjects. For a single site study, several personnel have been collecting longitudinal study data with low numbers of missing data. A pattern of increasing numbers of missing data has been identified with a newly hired data collector.
2: Variables known to be problematic are regularly monitored by curation team and delays in site resolution of issues are reported to governing committee.
3. Aggregate data are examined for inconsistencies such as lower average mortality in patients with GCS 3 than GCS 4-5.
1: Site visits for audit of subject hospital records against CRF and eCRF entries.
2: Submission of redacted hospital records for audit against eCRF entries.
3: Independent double entry of any data transferred to the database from paper form, either for full dataset or for representative subset.
1: Normal ranges are determined for each assay.
2: Assays are standardised as far as possible.
3: Assay substrate are defined (e.g. ionised vs. unionised fractions, whole blood vs serum, total vs protein bound as appropriate).
4: Normal ranges should consider/be customised to pathology or subject group in question.